To create a game plan (you can create up to 10), select New Custom Plan from the list on the left side of the Game Plan page. This will display a brief description and a New button on the right. Click the New button -- this will take you to the general settings page for the new plan. Enter a name and description and then select your base offense and defense for the game plan. These will be used if you do not setup the down specific settings. Additionally, your base offense style will guide general game decisions for your team.
After entering this information, click Save. Make sure you get a success message and then click on Offense in the top right --- this will take you to the Offense down settings. (You can also click Save & Next to save the general settings and go directly to the offense section.) Follow the same procedure for setting each offensive play you used setting the base offense (tabs are the downs) -- make sure to click Save or Save & Next on each down. Then do the defense the same way. When you are finished, click Back to return to the main game plan page.