We only really know ULib and ULX. Each mod and addon written by other authors are different.
Our install instructions are in the ULib_readme.txt and ULX_readme.txt files, under a category aptly named "Group: Installation"
Those two files are in the zip files you downloaded. They contain very important information, much of which answers questions we've been asked dozens if not hundreds of times.
As for other mods, most contain a readme.txt, or if you're getting them from Facepunch releases, most have install instructions on the front page.
