Need help starting GMod

I just bought Gmod yesterday from Steampowered.com. I downloaded it and ran it, but when i did, half way through loading, it stopped, and said file hls.exe has stopped working (looking for solution) and never did. i looked everywhere in those files and never saw it, also, can u tell me where i put weapon and vehicle add ons? that would be a big help.

Every addon with an info.txt file in it goes in the addons folder.

Also, for your problem, try to verify the game cache of Garry’s Mod, and HL2; HL2DM; HL2 EP1/EP2; TF2; Portal. Every game that gmod can mount.

i really dont want to seem dumb , but how do i verify the cache

[editline]10:50AM[/editline]

also, i cant find the addons folder

[editline]10:54AM[/editline]

found the addon thingy…lol

still, how do i fix the problem?