a/ Activating the second language of your site:
Please go to [Site \ General Properties],click on bouton . and select the languages you wish your site to be in.
b/ Domain name for the second language of your site
If you have reserved a domain name for your site in its second language, we recommend that you associate it to that language. To do that please go to [Account \ Domain Names].
c/ New domain Sitemap
To index your second domain name correctly, you will need to submit the sitemap file in the same way as when you submitted your first one.
Click on [Marketing \ Sitemap SEO] then .
Click on the image to enlarge it
More information :
How to submit my sitemap file to google?