thats all possible, theres a steep learning curve tho.
step (1) drawing and illustration
draw it all out and leave nothing to the imagination
these illustrations will help you make the mesh or polygons.
step (2) pick a modelling package.
scan in the illustrations and use them as reference shots behind your 3d window. learn to model the shape with the least amount of polygons.
step (3) skinning and texture wrapping.
if your modelling program has a good set of tools to make the skin then use it. You may need to get another program for this aspect.
step (4) making the skin
Using a 2d art package you have to draw on the skinned texture to resemble what you want.
step (5) boning and animation
Your going to assign polygons to bones and after this step your going to animate the bones to represent the animation sequences required for your character. eg: walk run fall shoot etc..
step(6) exporting.
always save your work in the native format so you can keep all that hard work on file and finally exporting the model to the .x format.