Just install it to the same directory as you installed the base to.
* To play campaigns, select "Campaign" menu where you will see all installed campaigns listed. Select the one you want to play and click "Select" button, then click "Continue" button.
* To play single missions, select "Tech Data" menu, then select "Mission Simulator" and "Single Missions". You can also play campaign missions you have finished by selecting "Campaign Missions" instead of "Single Missions".