Need to add new field - user picker

Dear All,

I need to create a new field for Engagement Manager for Opportunity.
The field should be user picker because I need to configure some kinds of notifications to be sent depending on the person chosen in the field Engagement Manager

How can I create that field?
Thank you for your help in advance.

Best regards,

If you want to simply create a relate field with User. Goto Studio->Fields
and create relate field by selecting related module as User and you are done!