Not loading game. ERROR

I just downloaded minecraft.exe or something along those lines and it says play demo, so i clicked on it and it took 10 mins for it to load then it said error. The second time to load took 5 seconds but also said error. Also if you download what I downloaded and signed up can you play the full version (multiplayer, creative, survival, singleplayer and so on)?
If you can, can you some how contact me and tell me how because im really confused.