If you're needing a tutorial on how to use mod managers to actually install mods then this playlist by Gamerpoets covers that very well and should teach you how to mod yourself and is the best guide I've seen. Pick and choose what you want (or use them since they all work together just fine), read the mods descriptions to make sure each mod something you actually want, the whole point should be to tailor the game to your personal tastes not anyone else's. Well since you didn't specify what sort of mods you were looking for I'll just go the whole way.
