Applying a planar mesh/texture

I’ve created a texture for my basic body model, and would like to put it onto the model, but I have no idea how, and I haven’t been able to find out, through searches or w/e.
I used UV Mapper to get the basic image, then I used paint to color it
the bottom model in the gallery(was made in Blender by Montage Studio’s tutorial on Modelling a Low-Polly Char)
how do I apply it in Blender, or is there another program?
please help

sorry I didn’t know what “words” to search for
Kept using "how to apply planar textures