You put mods into the game by creating a Downloads folder inside the Sims 2 Legacy or Sims 1 folders and putting any package files in there. A good creator will let you know if you need to put it elsewhere or use any special programs. I primarily use Mod the Sims, Boiling Oil, and More Awesome than You for my stuff. They've all been around pretty much since the inception of Sims and I've been a member of Mod the Sims site for nearly 20 years.
None of the original Sims servers or content is available from EA. I cannot give you any links to anything here, but I can direct you where to look. Garden of Shadows for Sims 2 and The Sims Depot for Sims 1.
