To install a printer the basic idea is that it needs to but plugged into the computer via USB and plugged in the power outlet. The hardest part of installing a computer printer is knowing how to get your computer to identify it.

What you need is the printer's Driver CD. This contains that software needed to install your printer correctly. Windows may try to install it but may not do it correctly. To install the printer correctly install the printer's driver.

Follow up:

If you lost the Driver CD you can visit the website of the manufacturer. If you printer is made by HP, visit the HP website. Once you are on the printer's website, go to support, then drivers. Find the model number of your printer. Then download the driver. If you cannot find the driver with this method, search Google for something like "HP Deskjet 3030 driver" and you will find the driver.

Download the driver to your desktop. Now click start and then right click My Computer. Click Properties. If in Vista, click device manager. If in XP it should be under the Hardware tab. A windows will show up that contains all of the computer hardware that is installed, find the HP Printer and right click it. Click install/update driver.

Now search for the driver on the desktop directory. The computer will now use that driver for the printer. The printer will no longer have a yellow question mark or exclamation mark in the Device Manager if it did.

Your HP Printer is now installed!

Related questions:

How do I install a printer on windows Vista?
How do I install a hp printer?
How do I find printer drivers?
How do I install a printer without the Drivers CD?