Actually nevermind that post, I figured out what was wrong and fixed it, quite simple really, the resolution settings were set for to low that nothing poped up...now all the stuff I dl is working, well it's showing but I don't know if it's working.
I downloaded some dat files but when I try to test one in the game, some of it dissappears. Also some other buildings also started dissappearing. Ive been using the program files/maxis/sm4/plug-in way but it still does the same thing the 'my documents' way,