Step 2 - Add application in Xero
1. Go to api.xero.com and login using your standard Xero login details
2. Go to My Apps
Choose to add a new application.
3. Under App name you can choose anything you like (for example Your Magento Store). Enter your company url and paste the Callback Url from Step 1 into the field "OAuth 2.0 redirect URI".
4. Then agree to Xero's terms and hit "Create App".
5. Click "Generate a secret"
6. Copy both the "Client id" and "Client secret" to your Magento admin settings under Stores > Configuration > Fooman > Xero - OAuth 2.0. Then press "Save Config". Please note that the Client secret will only be displayed once.
7. Press the button "Step 2 - Connect Xero Organisation"
8. Allow access to your User account information
9. Select the organisation from the dropdown menu that you wish to connect to.
10. Click Connect (or could be labelled Continue if you have previously connected to the same organisation)
11. You should now get redirected to your store's admin alongside a confirmation note. Select the Xero Organisation and hit Save Config.
12. Optionally you can connect more Xero organisations by clicking "Connect additional Xero Organisation" to repeat Steps 8 to 11. Please note that connecting to multiple Xero organisations is currently only supported if the same Xero user has access to all connected organisations.