Creating custom figures for poser:

1 - Model the figure (this process by itself, can have as many as 30 different tutorials involved in it)

2 - UVmap the figure (This process can have just as many tutorials).

3 - Rig the figure (even more tutorials)

4 - Texture the figure (gazillions of tutorials)

Each of those individual parts, by themselves, can fill a book, and have done so.  THere is no easy way to do it, at all.

However, ther books themselves are all available, and one of the ones with regards to rigging you'll want is "Secrets of Poser Figure Creation".

thou and I, my friend, can, in the most flunkey world, make, each of us, one non-flunkey, one hero, if we like: that will be two heroes to begin with. (Carlyle)