Just make your way through readme files (reading them, I mean

), FAQs, and suchlike. Many of these come with mods themselves. It's *very* important to do this. If you don't, you really won't have any idea what you're meant to do, and not to do. SImple as that.
For Wrye Bash, definitely check http://tesnexus.com/downloads/file.php?id=35230 out.
OBMM (or OBMMex, the Extended version, which I prefer, but isn't essential) is pretty simple to get up and running, plus it has documentation anyway.
OBSE is even simpler than either, by far. You just copy and paste key files from that which is unzipped from the obse archive. Mostly, you could either use v19 or v20. At the moment, v20 seems stable enough, IMO. YMMV. But v19 should be quite sufficient for
nearly everything.
Techinically, you could get by with only OBMM (or OBMMex), provided no mods you intend on using rely on obse (or Wrye Bash, in a few cases...) - but, as I said above, you really may as well "install" obse, as it's so darn easy. That one will open up options galore, so it's well worth it. Wrye Bash, on the other hand, is not often *essential*, but is extremely versatile and valuable, as tools go. It offers the better mod installation mehod (BAIN),
by far, as well. However, the learning curve is steeper than for almost any other mod or modding tool out there, in some ways. The Pictorial Guide is custom built to help alleviate this difficulty.
For modding in general, once you're on your feet already, try http://tesivpositive.animolious.com/ - chock full of good stuff, but not all that intuitive, if you're literally just getting started.
And once you get started, and are reading those things you should be, you can always ask specific questions here, and/or elsewhere, and people will generally be quite glad to help. The thing is, provided you're helping yourself to some extent, you *should*
always find that to be true.
edit: The other thing to remember is, don't let your eyes get bigger than your stomach.

Which is to say, only install one or two mods at once. Preferably *one* at a time!

Install one, test to see if it's working as it should be. Lather, rinse, repeat.