Most of the addon packs have release threads on FacePunch forums, just like we have a release thread on this forum.
Perhaps you can find the threads of the addons you have and ask questions in those Facepunch forum threads.
By the way... I've seen many addons compressed files include paths that make it difficult to know exactly where to extract to if you aren't used to what to look for.
Some to garrysmod folder, some to addons folder. Some even get more difficult than that.
A true 'addon' will have an info.txt file inside of it.
I think one of the most confusing ones I've seen was pheonix mod. It had like phx/phx/info.txt
When I dropped phx folder into my addons folder, it didn't work of course.
Instead of addons/phx/phx/info.txt, I had to drag the middle phx folder to addons, making it addons/phx/info.txt
As for help with non-addon mod packs, you'll have to see the readme files or release threads
