How to start DLCs

@playitagaincam2 The DLCs are started with war table missions, Trespasser is only available after completing the main game and you can't go back once you start it.

If your DLCs aren't showing, make sure you're logged in to both Origin and the Dragon Age servers, this is necessary so the DLC authenticates. 
Is any of the other DLC content showing up? There should be some Avaar and Qunari armour/schematics and decorations for Skyhold, Trespasser should make it so each of your abilities has 2 upgrades to choose from instead of one and in the options menu you should have the ability to activate trials to change the difficulty of the game.

The nug isn't a part of any DLC, it was a part of a patch, it allows you to upload all the collectables on a completed character so you can then use the nug on a different character to get those collectibles (schematics, potion recipes, decorations, etc.)