Need help finding Gmod Hammer editor

[Mash]

I have been using hammer editor for CS:GO and L4D2 but now I want to start using it on Gmod. Sadly I don't know what Source development kit to use for Gmod. Hopefully you or someone you know will be able to help me by either telling me or linking me to a tutorial.

Thanks in advanced

P.S I don't know if this is where I should put this thread but it is here now

 

[jb]

https://lmgtfy.com/?q=gmod+hammer+editor

 

[Dicknose]

D:\Steam\steamapps\common\GarrysMod\bin