Ok i found this tutorial about making a simple box model for using as a static prop model in source maps.

Tutorial (http://www.joespataro.com/html/props_tut_xsi.htm)

I have a problem with the texture editor. I dont know how i keep the texture on the box after i close the texture editor. I read another tutorial about the UV mapping, but i am still not sure how it works.

Maybe someone can clear this part for me. Thanks in advance.