need simple webdesign help

So hello there bored people!

I'm making this super simple website, like this:

H E A D E R |
--------------
S | C |
I | O |
D | N |
E | T |
B | E |
A | N |
R | T |
---------------
B A N N E R |


but if my content is too long i have this:

H E A D E R |
--------------
S | B |
I | I |
D | G |
E | C |
B | O |
A | N |
R | T |
---- E |
---- N |
---- T |
---------------
B A N N E R |

And as you can see, the side bar isnt long enough!
Could you help me? :>

Thanks in advance, skazi!