So, URL other users can add your app/page as a pageTab using aboURL but for that you need to share or provide above URL to users.
The Add Page Tab Dialog prompts
<p><a onclick='addPageTab(); return false;'>Add PageTab</a></p>
place this line of code in thetag of your HTML page:
YOUR APP ID should be replaced with your actual application ID.
That’s it.Now you can use interface for face page Tab.