How can I make my own character model?

Can someone point me to wiki pages or other threads that would help me create a custom character model and how I would go about animating it?

I basically already have the model I want to use as the character but I am not sure how to animate it or actually make it so you use that model instead of ROBLOX's character model.

Here is a model of it: http://www.roblox.com/Test-Character-item?id=378694327