Hello Atif,
Thank you for reaching out. Please refer to this guide for more details on how to create shopping campaigns and product groups within the campaigns using Google Ads API Beta. The code sample to add this listing group is currently available only in Java. You can use the logic from the available code sample to create similar request in C#. Please let us know if you still have concerns.
Regards,
Nikisha Patel, Google Ads API Team