Applying a material to a model which has preassigned materials I exported a model from Cinema4d into Blender. I exported it as an FBX file and in the file, there are already predefined textures:



This is how the model looked when I imported it into Blender:



Any idea on how I assign the specific materials to the specific areas such as the head and the body?
Select your object. Tab into edit mode.

Hit P. It will bring up 3 options


Selection
Loose Parts
By Material


Since you are asking about adding materials to different parts, you probably don't already have them.
If th mesh isn't solid (i.e., body, head and hat don't share vertexes) take the "Loose Parts" path.



This will turn each part of the mesh into a separate object. They can be colored separately.



alternately, you can mouse over a part of the mesh and hit L. follow this answer to color the selection.