#11 oauth content screen doc

Author: kamarton

docs/images/oauth-screen-continue.png

@@ -15,3 +15,75 @@ If you do not have an account yet, here is the description: [Registering to GCP]
 You can enable the APIs for the services you want to use based on this description:
 [Enable APIs on GCP](enable-gcp-apis.md)
 
+## 4. Create a "OAuth content screen"
+
+- In gcp console navigate to "APIs & Services" > "OAuth Content Screen"
+- Please fill in the required information. If you are using it for your own purposes, 
+there is no need to fill in all the information, as you will only be using it in test mode.
+
+  "SAVE AND CONTINUE" button at the bottom of the page.
+- Nothing needs to be filled in on the Scopes page.
+
+  "SAVE AND CONTINUE" button at the bottom of the page.
+- On the test user page, add the accounts for which you want to grant access.
+  *Remember, you can only add accounts that originate from Gmail or Google Workspace.*
+
+  "SAVE AND CONTINUE" button at the bottom of the page.
+- At the bottom of the summary page, the Oauth screen is ready with the BACK TO DASHBOARD button.
+
+On the OAuth Consent Screen, you will have the option to add additional test users in the future.
+
+This description does not cover the publishing of the OAuth Consent Screen.
+
+## 5. Create a credentials
+
+- In gcp console navigate to "APIs & Services" > "Credentials"
+- The "+ CREATE CREDENTIALS" button at the top of the page.
+- In the select, choose "OAuth client ID".
+- In "Application Type", choose "Desktop App".
+- Specify the name of the application, e.g. "gwbackupy"
+- Click to "CREATE" button
+- In the pop-up window, click on the "DOWNLOAD JSON" button to download the credentials JSON file.
+  
+  **Handle the JSON file securely. Do not share it with anyone and do not make it available on the internet.**
+- Copy the JSON file to a location where gwbackupy also has access and can specify its path as a startup parameter.
+
+## 6. First run of gwbackupy
+
+Run in CLI (terminal):
+```bash
+gwbackupy --credentials-filepath <file path of credentials JSON> gmail backup --email <email address of backup>
+```
+
+e.g.:
+
+```bash
+gwbackupy --credentials-filepath .tmp/gwbackupy-test-oauth-client_secret_368702422762-84sf6lcl949ipohkho8qtumceatudlre.apps.googleusercontent.com.json gmail backup --email [email protected]
+```
+
+If the parameters are correct, you will receive the following lines. 
+
+> Please visit this URL to authorize this application: https://accounts.google.com/o/oauth2/auth... 
+
+If the system is able to, it will automatically start a browser with the link. 
+*Please always check that the browser has started in the correct profile (in case of multiple profile usage).*
+
+In the browser window, select the email account specified.
+
+On the following page, click the "Continue" button. 
+*You will only receive the security warning if the OAuth Consent Screen is being used in test mode or by a test account.*
+
+![](images/oauth-screen-continue.png)
+
+On the next screen, click "Continue" again to allow the application full access to the gmail account.
+
+![](images/oauth-screen-grant-access.png)
+
+If successful, you will receive the following message in the browser:
+
+> The authentication flow has completed. You may close this window.
+
+Meanwhile, gwbackupy has already started in the background and has begun saving the emails found in the account.
+
+*This step is required for each account. Additionally, it may occur that the Google servers require 
+it again due to infrequent use or other security considerations.*