How to setup Amazon SES for aws-ses gem

[Synkevych]

How to correctly create and setup access_key_id and secret_access_key in Amazon Simple Email Service (SES), for aws-ses gem? In the description of the gem it is written to provide exactly them in the credentials file, but I can't figure out how to create them.
I tried to create a new user through Identity and Access Management (IAM) specifying full access to Amazon SES and using those keys, but it didn't work.