Links open in specified Div layer? HELP!

My problem deals with a theme I am making for my site. It is the first time I am really using the actual theme system instead of just sticking the wordpress index in a php include.
So, How can I make all links (comments, calandar, ect..) open in a specified Div layer?

My site is set up as follows
A Div that contains the blog, and a div that contains the calandar.
How would I make every link open in the blog div?

I hope I don’t sound too dumb. Thanks in advance to anyone who can help me.