This guide will walk you through “Ostagar”, in Dragon Age: Origins. We will go through how to go through this area, as well as any secrets you can find.
Map
Ostagar
You’ll arrive in Ostagar with Duncan after completing your origins sequence. You’ll immediately meet King Cailan, who will politely welcome you to the camp (regardless of what you say to him), and then Duncan will tell you that you’ll soon need to complete a ritual called the Joining in order to become a Grey Warden. But in the meantime, he’ll invite you explore the camp and take some time to recover from your trip.
You won’t be able to do much in the camp. You’ll meet a shopkeeper (#11), two fellow recruits in Ser Jory (#8) and Daveth (#11), and a junior Grey Warden named 
Alistair (#14), but most people will be too busy preparing for the upcoming battle to pay much attention to you.
Eventually, you’ll need to return to Duncan (#4). He’ll tell you that before you can undergo the Joining, you’ll first need to prepare for it by obtaining three 
Vials of Darkspawn Blood (one for each recruit) from the Korcari Wilds. He’ll also ask you to visit an old Grey Warden archive in the Wilds and see if you can find the 
Ancient Treaties that were stored there. Then Alistair, Jory, and Daveth will join you, and you’ll be ready to depart.
1 – Soldier
The soldier will give you an overview of the camp, and you’ll receive the Culture and History 
codex entry for Ostagar by talking to him.
2 – King Cailan’s Tent
You won’t get to meet the king here, but if you persuade the guard out front to be talkative, then he’ll mention that King Cailan is married to Teyrn Loghain’s daughter.
3 – Teyrn Loghain’s Tent
If you’re persuasive, then you’ll learn from the guard outside the tent that the king and the teyrn have been arguing of late. You might also be able to convince the guard to grant you an audience with the teyrn. If you’re successful, then you’ll gain the Culture and History codex entry for King Maric Theirin.
4 – Duncan
You’ll find Duncan by the campfire here. If you’re playing a Human Noble, then you’ll also find your mabari war hound here.
Note: If you get caught pickpocketing in Ostagar, then Duncan will chastise you for it (and you might even spot the knight reporting your actions), but nothing will come of it.
5 – Ash Warriors
When you first approach the ash warriors, you’ll find the ash warrior leader in conversation with an elven messenger named Pick. If you wait for Pick to leave and then talk to him yourself, you’ll be able to lie to him and convince him that he should give you 
Ser Garlen’s Sword. If you talk to the ash warriors, then they’ll tell you about their fighting style, and how they fight with mabari war hounds.
6 – Kennels
Depending on the type of character you’re playing, the kennel master might give you the quest “The Mabari Hound.” He’ll tell you that the mabari hound in the cage next to him is sick from drinking darkspawn blood, and he’ll ask you to muzzle it so he can give it some medicine. If you succeed, then the kennel master will ask you to look for a special flower in the Korcari Wilds, which he’ll need so he can treat the dog. You can also just kill the dog to end the quest quickly.
If the kennel master doesn’t give you the quest, then you’ll trigger it when you pick the flower in the Wilds. Either way, when you bring the flower back to the kennel master, you’ll be able to demand payment, and the kennel master will reward you with 50 silvers and 500 xp (if you don’t demand payment, then you won’t receive the silvers or the xp).
Note: 
Human Nobles will automatically gain access to a mabari war hound companion at the start of the game. For all other characters, they’ll either need to complete the kennel master’s quest with the hound surviving (and then meet the hound again later on) or they’ll need to re-visit Ostagar in the Return to Ostagar DLC.
In the evening you’ll also find a note in one of the kennel enclosures. It will give you the Culture and History codex entry for Dogs in Ferelden.
8 – Priest
At this spot you’ll find a priest leading some soldiers in prayer, and she’ll offer you a blessing if you’re interested. You’ll also meet a recruit named Jory here.
9 – Gate to the Army Camp
You won’t be allowed to go through the gate.
10 – Prisoner
The prisoner will give you the quest “The Hungry Deserter.” He’ll tell you that he hasn’t been fed since he was locked up, and that he’s now starving. He’ll then ask you to get him some food. If you ask him why you should bother, then he’ll offer you the key to a mage’s chest (#12) in exchange.
There are two ways you can get the key. If you’re feeling evil, then you can simply kill the prisoner and take the key, and then tell the guard that you were defending yourself. You can also actually help the prisoner. To do that, you’ll either need to persuade or bribe the guard (10 silvers) to give up his lunch, and then give the meal to the prisoner. The prisoner will then hand over the key as promised.
Of course, when you head over to the chest (#12), you’ll find a tranquil mage standing next to it, and the mage will prevent you from doing anything with it. To get the chest open, you’ll have to wait until evening (after you’ve completed your Korcari Wilds quests), when the tranquil mage isn’t there any more. Inside the chest, you’ll find several useful items, including an 
Enchanter’s Arming Cap and more.
Note: If you miss out on looting the chest during your initial visit to Ostagar, you’ll get a second chance in the Return to Ostagar DLC.
11 – Quartermaster
The quartermaster will sell you a variety of regular goods, including arms, armor, and a pair of 
Backpacks (you can buy one in the afternoon and one in the evening). He’ll also have some higher quality “other goods” for sale, but you probably won’t be able to afford them. You can also meet the recruit Daveth here.
Note: If you pickpocket the quartermaster, then you’ll gain 
Hardy’s Belt.
12 – Tranquil Mage
The mage will tell you about Tranquility and item enchantments. This will result in you receiving the Magic and Religion codex entry for The Tranquil. The mage will also prevent you from opening the chest next to him (see #10 for how to get the chest open).
13 – Wynne
Wynne is a mage. She’ll talk to you about the darkspawn and the Fade. At the end of the conversation you’ll receive the Characters codex entry for 
Wynne.
During the afternoon you’ll meet Alistair here. When you talk to him, you’ll learn that he was a templar before becoming a Grey Warden, and you’ll gain the Characters codex entry for Alistair. In the evening, this is where you’ll undergo the Joining ritual.
15 – Guard
When you first arrive in Ostagar, you’ll find a guard here, and he’ll prevent you from heading north towards the Tower of Ishal (Exit B). You won’t be allowed into the tower until after the Joining.
16 – Main Gate
You won’t be allowed to go through the gate.
