I'm guessing it's polys going by what you said in another post about using polys. You should be able to either map your UVs (Edit Polygons --> Texture --> then either auto mapping or plain*something or other i can't spell) then goto Window --> UV texture editor and click file --> UV snapshot. This will save an image of your mesh layed out flat that you can paint textures on. Then just assign this image you painted onto to your material like Phopojijo said (hold space bar click materials --> assign new material --> Blinn, then click the checkered box next to color, then click file then just browse for the file you want).

OR

Easier this way, Just select the faces that make up your screen, then just add a material and use a screen grab for it's color.

I would do a quick tutorial for you but i don't have access to maya here to take screen grabs. If your still having problems in the morning i'll post one then.