Choose the file named xeroapp.zip (which you have downloaded at Step1).
Click on the upload button.
Once you click on upload button below page is shown
Hope you have understood the 3 step installation process of Xero.
Once the installation is complete, then please follow the steps for the below steps
Go to the Invoice/Quote module List view, and click on Connect to zero Button at top left. It will navigate to the Xero Authentication window.
Enter username and password of your Xero Account and press on login button. It will navigate to custom page.
Select the invoices which you want to sync with Xero, and press Submit button.
This is the Xero invoice page. Here you can find the synced invoices from CRM
This is the Xero Contact page. Here you can find the synced contacts from CRM.