Model textures Problem!

I am currently having problems with adding textures to my models in game!

What I have tried and info

I was just browsing a youtube video on how to do this and my engine doesn't show the "material selector" window.. I can't find where to enable it :S

Installed beta 3

Still has not fixed the problem..
There is still no material selector..
There is no "material change" option. Its just not there :S

Ive spent more then 4 hours trying to fix this problem myself but Ive gotten no where.

If anyone knows how to solve this please post here.

Also It says my model has over 100 textures when it only has 1