Help with menus and width of screen

Hello,
I have 2 issues with my current site:
http://www.thewebsitewarrior.com

I do not know php but I can add html code to the php pages, which I have already done to modify other things.

1. On my home computer, my site is displaying fine at screen res. of 1280. However, on my sister’s computer, screen res. 1980 the window width stretches which causes my left side ads to appear next to each other horizontally, instead of vertically, causing the left sidebar to be wider than it is on my screen.

Could I change the width of the window to a fixed width? How would I do this? I’ve checked some of my php files but I didn’t see anything that looked like settings for window width.

2. I want to create several menus in the left sidebar, each with their own heading. This theme only allows one menu in the left sidebar. Is it possible to have multiple menus when the theme only has one? How would I do this?

I like this theme accept for the above 2 issues.

If my needs aren’t possible in this theme, could anyone recommend a theme that would feature:
3 columns
multiple navigation menus leading to static pages, each with their own heading
fixed width screen, or at least a variable width where the width of the sidebars does not change.