Step 1. Enter into the Promo page, click on the setting icon at the right-hand corner.
Step 2. Unfold the manager list, click "Add my fan page tab"
Step 3. Select the fan page you want to insert the tab, remember to click on "set" button.
Step 4. It's done! You can check it on your fan page.
Also, you can add your promotion to other Fan Page as well. On your promotion page, click the menu on the upper right-hand corner of your promotion header, you will find the function link in the menu.