Every Facebook application includes a collection of text links in the top left hand corner of the page. Click the link titled “Add to my Page.” This will add the app to your page.
Once you’ve added the application, go to your Facebook page and, again, look for the top-left menu of text links. Click on “Edit Page” – the first link on the list.
The resulting index will list all the applications installed on your page. Scroll down until you find the application you want to configure.
Click the pencil icon to the right of the application, and then click the first item in the drop-down menu: “Edit.” This will enable you to configure whichever settings are needed to run the app at hand. (For example: JD Supra login info to tether your profile to Facebook with JD Supra Docs; a call to action for the Email Signup app; a legal subject for Legal News; etc.)
Final step after configuration: installation on your Facebook page.
Return to your Facebook page. Click the + sign at the end of the tabs listed on your page. Select your newly configured app in the resulting drop-down menu. The app will then appear as a new tab on your page.
If you are installing an app that also works as a box on a Wall or Info page, go to your Boxes tab.
Find the app that you want to install as a box, click its “Edit” pencil, and choose the first item in the drop-down menu: “Move to Wall tab.”
The app will now appear on your Info and Wall tabs as a box in the left hand column of the page. You can drag and drop the box to determine placement in the column.
Information from http://scoop.jdsupra.com.