Hey, what you need to do is locate the "My Computer" icon. This is placed in different places depending on what operating system you are running. If you run Windows XP and are using the modern start menu, it is in this place. If you are using the old start menu or an older OS (e.g. Windows 95, 98, 2000) then it is on the desktop.
Right click on this icon and select properties on the drop down list.
Go to the "Hardware" tab on the new window and click on "Device Manager"
Open up the drop down box titled "Display Adapters" and you should have the details of your graphics card.
One word of advice, if you're thinking of upgrading your card and you dont know much about computers, get someone who knows about computers to upgrade it for you. Either a relative or preferably a computer repair shop such as PC World etc. They charge a small price but it's worth it for the correct installation of a device if you dont know much about these things.
Hope this helps