I dont like it, but I got some tips for ya.
1) Try to create your own button layouts in Photoshop or others...
2) Don't use fixed widths and heights.
3) If not already, learn to code it according to XHTML/CSS rules
4) Add a background for the menu and the contents.
Lastly, I am pretty sure that you are using a website designer program or something like that?
Am I right? Well, I mean one that has drag and drop and such. I forgot the name of it, but I used that for my first pages aswell.
Learn XHTML and CSS, and learn the "rules" for coding in it, things like table-less designs and cross-browser compability.
XHTML and CSS coding has so much more to offer, and you can create much better websites. Simple JavaScript wont hurt either...