This is how you can apply a texture. Any texture. Since the colour comes from the texturemap, the first step is to change that horrible purple to white. Ctrl-click on the coloured box -- "Diffuse Color" -- and you get a fairly conventional colour menu popping up. Change the "Specular Color" to black or a very dark grey.

Then click on the tiny little square next to the Diffuse Color, and work through 2D Textures to image_map. Click on the name in the Image Source entry, and use the Browse button to find the file you want.