is it hard making maps for Gmod?

hi!
recently ive been downloading alot of stuff for gmod and at times i cant find what im looking for (which is a detailed war zone for NPC wars) so im wondering whats the programme you make maps and stuff on and does it cost?
and how hard is it to make a map?

thanks

To make maps is free and straightforwards, although it can be confusing at first. Visit the mapping forum for more information. But the basics are in your steam tools tab, download the SDK and in there is a program called Hammer. That’s what people use to make maps for source.

To clarify: Making maps is easy, but making maps that don’t look like shit takes skill and time.

anytihng else i should know?
are there starting materials and stuff?

Introduction to editing
Your first map in hammer

It has all ready.
Every material, entity, and other things from HL2 are all there.