If you are not worried about losing all of the data (all of the pictures, videos, music etc...) on that computer, do this:
You need to boot to the CD. Do this:
When you first turn your computer on, before windows loads, you will see a message that says to press a certain key to enter setup. Pay attention, as the message may flash very quickly. It is usually an Fkey or esc or del. Tap this key as the computer starts up - before windows starts to load.
This will take you into BIOS. You use the arrow keys to navigate through BIOS.
In BIOS you want to look for Boot order or Boot sequence or maybe even just Boot. You want to set your CD drive as the first boot device. You usually use the plus and minus keys to move your devices around in the boot order.
Once you have your CD drive set as the first boot device, place the CD in the master CD drive. Now exit setup and SAVE changes (F10).
The computer will now reboot. You may see a message that says: "Press any key to boot to CD". Just keep tapping the space bar as the computer is starting back up (before windows loads). You will hear the Cd start spinning in the drive and see a blue screen with the word "setup" at the top.
Once all of the files have loaded, enter setup. Press F8 to agree to the license agreement. Now you should see a screen like this one:
You want to install a fresh copy of windows.
Follow this order
1. Delete partitions
2. Create a new partition
3. Format your partition (to setup windows on the selected item press enter)
Keep in mind that this will completely wipe out the hard drive and erase all of the data on that computer! Make sure that you have your windows product key. You need it. Setup will let you get this far, but if you don't have that key You will be left with a blank hard drive!
If you choose to do this, the very first thing you should do after the install is make sure that all of your drivers loaded.
Click Start then Run and type in
devmgmt.msc and press enter.
If you see any yellow exclamation marks you will need a driver for that device. Your computer should have came with a driver CD. If you don't have it the Emachines website will have drivers available for download.
Post back if you need anymore help.