That design is really cool. Hopefully it's aligned to your target audience? (I haven't checked to see what age your tutorials are for)

The only really constructive comment I can make on your design is that the tables in the center would be better if they were done in the style of the menu, without that double border, but with the background color instead.

As a coding suggestion, I woud suggest that you might like to use css, rather than tables, for your layout.

e.g. the table rows I mentioned above could be rendered with the following code:


However, since you seem to be using dreamweaver, if you've done this without touching the code at all you may prefer not to go this route.