need help

[wack]

hi guys ,i am wack and recently purchased htc desire rather than the iphone,however when i go on line and want to view videos it says i have reached my window limit and wont let me go any further ,how can i find out what the limit is?how can i close the other windows that are open
? as i cant see any indication on the screen ,if any one can help i would be really happy ,cheers guys ,wack.