The Silver Covenant
The Silver Covenant is the main Alliance faction for the Argent Tournament. Doing almost any quests at the Argent Tournament will raise your reputation with The Silver Covenant as well as the other "Alliance Vanguard" factions.
When you reach max exalted with The Alliance Vanguard you will notice your Silver Covenant reputation start to increase when running Northrend Heroics. The Silver Covenant have a Quarter Master that is located at the Argent Tournament Grounds in Northern Icecrown.
Raising Your Reputation
The best and fastest way to raise your reputation with The Silver Covenant is by completing the dailies at the Argent Tournament Grounds. The second best way to raise your Silver Covenant reputation is by running heroics without a faction specific tabard on. However, usually players will do a mixture of the two.
Below is a list of both sets of dailies available to you via the Argent Tournament Grounds. In order for the Champion Seals dailies to become available to you, you will first need to become a Champion of a city. To do this you will need to collect 25 Valiant Seals and turn them into your reputation specific NPC.