do first then a simple tutorial on the website:
www.anim8or.com
if you have done 1 tutorial you'll understand more. and know how you must do things.
i've copied the adding texture part from a tutorial:
To add your materials, select Options->Materials from the menu to show the material panel. Double click on the "New" material and select the stem's properties. Then select the stem and click on the "Apply" button at the top of the material panel.