Once you are logged in, the easiest way to find them is to search out either "McAffee" or "Norton" - yes, military members get both for free. These are not trials either, you will get the full version of whichever you like. Otherwise, you can go to the "Self Service" button, choose "AntiVirus Services", then click on the link that you want to download (either McAfee or Norton).
When you have downloaded the version that you want, make sure that you follow all of the instructions as they pop up. You will want to uninstall all of your other Antivirus and Antispyware before you download and install another one, or the current version might flag it and not allow it to be downloaded or installed.
After you have everything set up and installed, make sure that you run a complete scan on your computer to get everything rocking and rolling correctly.
Sound simple enough? It really is for those that have the military ID or CAC card to get into the AKO/DKO account. There are also tons of other free extras and goodies that you can get as a military member as well, such as Rosetta Stone software to learn any language you want and free college classes.
Be sure to check out this McAfee Antivirus for Windows 7 review to find out about all the great features of this security software.