Hi Arnab,
Thank you for reaching out. Please see this guide for creating UserLists from different audience types. If you are adding this audience to an ad group, you can use the CriterionUserInterest targeting type (same process for adding to campaigns but under CampaignCriterionService). Please see here to find the different Criterion IDs available for in-market and affinity types. You can see these targeting samples to help you get started. Let us know if you have any further questions or concerns.
Regards,
Anthony
Google Ads API Team