The Secret Ant Missions are rather simple to get to, if you know where to look. You also must have the Counterstrike expansion installed. If you don’t, don’t waste your time reading the rest of this page.
Simply start Red Alert as you normally would. At the main menu (shown above), hold down the left Shift key and left-click on the speaker (circled in yellow) in the upper right-hand corner. The program will then ask you to select the difficulty level. After you have done this, a window will pop up asking you to insert the Counterstrike disc in your CD drive. Put it in, hit Enter, and the Secret Ant Missions should automatically start up.