Abbreviated from https://blogs.dropbox.com/developers/2013/07/using-oauth-2-0-with-the-core-api/:
Step 1: Begin authorization
Send the user to this web page, with your values filled in:
https://www.dropbox.com/oauth2/authorize?client_id=<app key>&response_type=code&redirect_uri=<...
