Have you tried Tomlong75210's FCOM install guide? http://sites.google.com/site/oblivionpoinfo/walkthroughs/fcomguide
+1 <-- this suggestion.
It's the best guide around, especially for those who don't know almost everything they need to, to begin with. And, let's face it, that's most of us.
edit: I also strongly recommend the BAIN installation procedure, over OBMM. There are good, solid reasons why, as you will discover, should you give it a go. Well worth it, despite a little bit of a learning curve. It actually makes things
easier in the long term, and you can - with ease - undo just about anything you've done, which is fantastic for changing your mind, fixing issues, and simply updating mods (which happens
a lot... or
should, anyway!)