I want to create a Gmod map

I know I can’t use hammer.exe, as it doesn’t work, and tuts that I have watched on youtube are of no help.
Please, would someone, anyone tell me how to make a gmod map, step by step?

What do you mean you can’t use hammer?

It crashes every time I use it.

Use hammer from HL2 or CSS

Wait…That’s it?
Edit: Just installed HL2 and ran hammer from there. Problem solved.
Thanks.

You should combine both HL2 and CSS to get both more materials to work with but also models to give the map more detail.