1. Go to https://developers.facebook.com/ and login with your Facebook account
2. Click "My Apps" on the right of top menu and then click "Add a new app"
3. Fill in required fields
4. Go to Settings->basic to find your App ID and App Secret keys 
   
   
5. App must be approved by Facebook before we can use it. Go to "App Review" page.
   
   
6. Click "Start submission" and choose "Page Public Content Access" from permissions list.
   
   
7. Click "Add 1 item". When popup closes, fill in all required details and submit app.
8. App Access Token can be found on https://developers.facebook.com/tools/access_token/. Find the row with your recently created app and copy App Token
9. To find your Page ID you can use any free online tool like http://findmyfbid.com/ or you can follow official or follow the steps here https://www.facebook.com/help/community/question/?id=10209246525787871

UPDATE: If you want to show your own page where you have admin permissions, you should be able to do it without even submitting it for review. 

Snipped from FB: "While you are testing your app and before you submit it for review, your app can access content only on a Page for which the following is true: The person who holds the admin role for the Page also holds a role in the app as app admin, developer, or tester."