After you've downloaded the ZIP file extract the contents to your desktop.
Step 2:
Next you need to run the "Setup" file within the "Halo CE" folder. This will bring you to the installer.
Step 3:
Once in the install window you'll want to click "install".
Step 4:
Once you reach this step you will need to go back into "Halo CE" folder and locate the "Needed for installation" Folder, within it there are a list of keys you can use.
Step 5:
Once you find the file with the list of keys enter each one until you move past this screen.
Step 6:
When you arrive at this screen you will need to uncheck the "GameSpy" option, then click the "Change" button.
Step 7:
Before you go any further you should make a folder on your desktop where you can install the game in. (this is so your school wont be able to notice a changer in the system files).
Step 8:
From here you will need to navigate to the folder you created on your desktop in the past step. (If you cant find your desktop right off the bat navigate to your user file and look some more)
Step 9:
You can now proceed to install Halo CE.
Step 10:
After the game is installed you will need to exit the the installer and locate the patch file from above named "halopc-patch-1.0.10". Once found all you need to do is run the patch.
(If you downloaded the combo, this file will be where the product keys were)
Step 11:
After the patch is installed you can proceed to launch the game. You can find the game on your desktop or in the location you previously installed it to.