Currently, your upload page does not have an insert record server behavior on it to store anything in the database.
You state initially that you want the upload page to store to the database. When you add the Insert Record Server behavior, there will be a setting to redirect to a specified page after the record is inserted. Use this setting to redirect to the thank you page.
If you do not add any other behaviors to the page and want to redirect after upload is successful, use the Server Redirect server behavior. On the Server behaviors panel, clickthe plus button and select WA Utilities -> Server Redirect.
