Instructions
Decide what version of Half Life 2 Episode 1 you want. You will need a copy that can be installed with a disc to avoid using Steam. Half Life 2 Episode 1 is available as a stand-alone game as well as part of a package called the Orange Box that features Half Life 2, Team Fortress 2 and Portal.
Locate and purchase the type of copy you want. You can buy a copy from online stores such as Amazon and ship it to your home. Alternatively, visit a local store, such as Best Buy, that sells video games and purchase a copy of the Orange Box or Half Life 2 Episode 1.
Remove the contents of the box once you receive the game. Inside you will find a disc that you will need to insert into the DVD/CD drive of your computer and close the drive. Once you insert the disc, the auto-installation feature will appear on your screen.
Click on the "Install" button to begin the installation process. Follow the onscreen instructions to complete the installation. If you are installing only Half Life 2 Episode 1, you will need an existing install of Half Life 2 for the content to work properly. If you are installing the Orange Box, then Half Life 2 as well as Episode 1 will be installed.