I just beat level 3 on the main levels category in the single player menu but when I go to the page it says that I haven't beat it yet

You don't get an achievement for beating a player with level 1, 2, 3, and 4.

thats weird, did the popup screen saying you won come up? if not then the system didnt register it and you may have to do it again
:(, but if if the screen saying you one showed up then i dunno, you probably still have to beat it again

You don't get an achievement for beating a player with level 1, 2, 3, and 4.

I think the OP is referring to the Single Player level 3 challenge, since he cites "single player menu" in his original post.

Jaimie, if you happen to play through it again and still don't get the credit for defeating the challenge, submit a bug report here http://warlight.net/ReportBug so Fizzer can investigate the issue and hopefully get it resolved for you.

I just read what he meant, Guiney... Now I feel stupid

if memory serves, you can't beat the map with the use of saving.. *as it can be used to exploit getting different random seeds per save game* and you need to have access to the internet at the time you complete it.. I can't remember preceisely, but I do believe that single player games can be played without an enduring internet connection, your records are just likely to be forfeit.