How do I create a map for gmod?

I`ve used the tutorial at gMod wiki. It doesent appear any errors, but the grid is totally lame, and I cant change the size of it. And I cant make any textures.

Just use Episode 2.

Ok

[editline]11:58AM[/editline]

Hey, you mean choose ep2 instead of orangebox?

[editline]11:59AM[/editline]

In case, I can´t choose that.

that’s because you don’t own it, use counter strike source instead under “Source Engine 2006”