Is there any way i can make my website size adjust/change automatically to the resolution size of the users computer. Any code that can be used?
This is an issue most developers struggle with. I usually decide on a minimum resolution to support (usually 1024) and build the site accordingly
Problem with fluid is there's a BIG range of screen sizes at the moment. Netbooks at 1024x600; 'normal' laptops (going rate seems to be 1366x768) and people with HD at 1920x1080...and that's just 16:9. There's still a lot of 4:3 monitors floating about. So if you design for netbooks, say, your site is going to be squished up right across the top of a big monitor.
Depending on how you set up your site, you can try setting the minimum and maximum widths of your main div tag container to accommodate a wide range of screen resolutions. For example: max-width: 1024px; min-width: 775px;
Fluid width would be what you are looking for, however to do this you must know exactly what you are doing as overlooking certain areas will leave the site looking terrible to some users. Read a good article about it recently http://www.smashingmagazine.com/2009/06/09/smart-fixes-for-fluid-layouts/