Open your Blender File with the solar system.
Right click Mars so it is selected. A pink circle
should appear around Mars.
Press the F9 KEY or click the editing button.
Click "Set Smooth" in the bottom corner.
Change the two names next to ME and OB. 
Press the F5 KEY or click the shading button.
Click Add New.
Change the name of the material to Mars material.
Click Shadeless. (Shadeless means there will be no shadow)
Click Add New in the texture box.
Name the texture "Mars texture."
Click Map Input. Click the button that says sphere.
Click the Textures button.
Click on the two triangles next to the word none.
Click Image.
Click Load.
Click on the two triangles.
Click the white folder that says desktop.
(For the next step you have to have a folder named Blender Planets on your desktop. This folder should have pictures of the planets in them. These pictures have been specially formatted to fit around your spheres.)
Click on the white folder that says "Blender Planets."
Click the folder named "Mars."
Click "Marsmap.jpg"
Click Select Image.
Press the Shift P KEY. This gives you a preview of the Mars.