I read some tutorials and I just became more and more confused. I tried downloading S3PE and it's just not working for me. I have a mac, not sure if that makes a difference, but I just got this game yesterday and was hoping someone could help me get custom content for it.

umm... you can't?

modding on mac, that's new...

Post #37 in How to Mod Your Game for Beginners:
"I thought it would be useful to post instructions for Mac players too, though it's basically the same but a tad more complicated.

Go to your Applications/The Sims Medieval folder. Right-click on the The Sims Medieval icon, this will prompt a pop-up menu, choose the first option, something like "show contents of package" (you need to have the right-click option enabled for your mouse, otherwise ctrl-click should work too).

Place the Resource.cfg file in Contents/Resources/transgaming/c_drive/Program Files/Electronic Arts/The Sims Medieval

Create (or place if you have downloaded one) the Mods folder in Contents/Resources/transgaming/c_drive/Program Files/Electronic Arts/The Sims Medieval

Create (or place if you have downloaded one) the Packages folder in Contents/Resources/transgaming/c_drive/Program Files/Electronic Arts/The Sims Medieval/Mods

Place the d3dx9_31.dll file in Contents/Resources/transgaming/c_drive/Program Files/Electronic Arts/The Sims Medieval/Game/Bin

Place custom content in Contents/Resources/transgaming/c_drive/Program Files/Electronic Arts/The Sims Medieval/Mods/Packages"

Thank alexpilgrim for this.