uv mapping is when u take a 2d image and wrap it around a 3d object. First in the materials panel make sure u have the TEXFACE button pressed. (its above the color sliders) Split the 3d screen and change the new part to uv image editor. Then in the 3d window select the mesh u want to use and hit U key. then its just a matter of experimenting to find waht unwrap u are comfortable with, but BEWARE, LCSM UNWRAP HAS TO DO WITH SEAMS WHICH U CAN ADD IN EDIT MODE. Seams mark where the mesh will be “CUT” and unwrap. In edit mode u can add a seam by selecting a line of vertices u want to mark as a cut and hit CTRL+E and select mark seam. This is rather hard to do on non symetrical meshes. Its useful in animation and game engine because u take a mesh and “unwrap” it then u can save the layout as a targa(go to the UVs tab in the uv image editor window and look for the SAVE UV FACE LAYOUT selection and click it. the buttons window turns into a new GUI adjust the settings and paths then click export. the pic will be called what ever the mesh was named) and take to gimp and make the targa layout layer semi transparent then add a new layer make sure its transparent. then make it semi transparent. then just select the new layer u made and paint waht ever u want. THen add bump maps, spec maps etc. from the filter tab i believe. Make sure that all the red lines are covered save and go back to blender and in the uv image window click on the image tab and load that pic. Then in the uv tab click stick an ur done
Thats the hard way. If u have a pic all ready just load it into the uv image window and unwrap the mesh and u can use that pic on it.
DONT FORGET TO CLICK THE TEX FACE BUTTON IN THE MATERIALS BUTTON. THE UV MAPPED IMAGE WONT APPEAR IF U DONT.
Hope this helps cause it took a hell of a long time to type.