Step 3: Add a Data Feed for Google Shopping

From My Account, click the Add Feed link.
Enter a store name, select your shopping cart, and create a new Standard feed using the Google Shopping template.
After the feed is created, continue on to the Modify Feed Settings page.
Follow the on-page instructions and enter the Source Settings for your store. Click the question mark icons for instructions.
Enter the SFTP settings you configured in Step 1.
For the feed file name, use your store name in lower-case ending with .txt. The zipped file name will appear as you type, and should match the file name you registered in your Google Merchant account.
Examples:
www.mystorename.com => mystorename.txt
www.mystorename.co.uk => mystorename_co_uk.txt
www.mystorename.com.au => mystorename_com_au.txt
www.mystorename.com targeting Canada => mystorename-canada.txt
www.mystorename.com targeting Australia => mystorename-australia.txt
Click Update.