When you don’t know anything to begin with, 3D modelling/mapping is quite an ordeal to wrap your head around!
To get started modelling characters, I recommend this tutorial.
Also, here’s my favorite texturing tutorial (not for characters, but there is some useful information nonetheless)
However, I would also advise that you begin with simpler things. Try making your own props first (books, bottles, cans, etc), just to wrap your head around the process.
Also, almost any 3D program is fine to use once you know how. Technique is LEAGUES more important than the specific program you might be using. I personally use Maya for 3D and Photoshop for 2D. Zbrush is an excellent sculpting program.
I know a guy who’s a wizard with the free Blender software. It’s user interface is confusing, but it’s extremely powerful (and free!) once you figure it out.
Asking someone when you have a problem (after trying to solve it yourself first) can save a lot of time.