about UFO, how to play combat?
 

well, i might sound like somekind of noob, but how do i trow grenades and stuf? how to get things out of my backpack, or from my belt?

In order to throw a grenade, you will first need to Prime the Grenade. (The numbers equals turns before exploding) Then you throw it.

As for getting things from your backpack or belt...
Do you see the little icon resembling a lone man? Click it and you enter the inventory. From here you can move your equipment around.

8)