Your resolution sets how you view things on your computer. The lower the resolution, the bigger things will be, but the less you can fit at one time. Layouts sometimes are made to be seen in one resolution. The following resolutions that I know of are:
640x480
800x600
1024x768
1152x864
1280x720
1280x960
1280x1024
I use 1280x1024 so I can see as much of a webpage as possible.
How to Change your Resolution:
I'm not sure if this is the same for all computers but I looked it up and it should work for For Windows 95, 98, 2000, Me, XP and NT 4.0 users.
1) Go to the start menu
2) Go to Settings
3) Go to Control Panel
4) Click on Display
5) Click on Settings at the top
6) Where it says screen area or screen resolution, drag it to the one you want. I suggest 1024x768 because that's what most layout makers on bloop seem to use, but it's up to you.
Another way: On your desktop, right click and choose properties, skip to set 5.
I remember on ME that there was a small icon in the bottom right of the screen that looked like a computer, and if you right click on that it just had the different resolutions you could choose. And of course, ME is screwey so you'd probably want to restart your computer afterwards, at least that's what I used to have to do until I got XP.