I've been trying for a long time to get nexus mods to work on my fallout 3 game but none take an effect in game I'm running it on W7 if that helps

You put the esp files in your data folder. If you have the default game launcher, click Data and then check the mods you also want to load. If you have FOMM simply check the mods you want. If you do not do this, they will not show up in game, as this is how you choose what to have and not have active in your game.