text scrollbar / thumbnail scrollbar

hi there,
very new to wordpress and code; don’t really have much of an idea of what i am doing.

my pages look fine in safari but in other browsers the text runs past the box i have made for the content e.g., here. how do i insert a vertical scrollbar for the text? preferably a nice looking flash-like one? also how can i scroll between the thumbnails at the bottom of the posts? right now you have to click a post for it to scroll over to the older thumbnails/posts.