pop up window sizes

Hi guys...new to this net book scene and already going mad!!!
If a window opens up to scroll down and read something,fine.......if I get a window that pops up with no scrolling on the side bars,how do I view the bottom of the page to check a tick box??? It just seems that if the page don't fit,then tough luck......you just can't view it!!
I am probably missing something simple,but damned if I can find it.
I am using a 2 weeks old Acer Aspire One...10.1 inch screen,with W7 starter.
Many thanks...Jeff

 

BUMP...

So know one on here knows then??

I need to install an adobe update an a player update,but can't access the bottem of the pop up box to tick the box.....

Anyone ??