I need help... I can connect to the net and browse things but mu computer will not let me sign into any sites or download nothing...

Hi there

Probably browser settings. Cookies disabled perhaps.
Just reset all settings to default in Control Panel -> Internet Options.
If it still doesn't work the goto:
C:\Program Files\Internet Explorer
Find the file iexplore.exe and right click on it. Select Run as Administrator.

If you are able to download after this then try downloading a different browser like Firefox. (Firefox web browser | Faster, more secure, & customizable (http://www.firefox.com))

Please let me know of this helped.
Cheers
Grant