Point elastic beanstalk server to subdomain

Hello everyone beginner here, I have setup elastic beanstalk now i want to point it to my subdomain (namecheap) Given i'm using the free tier can anyone here help give some ideas how to do it.

My Api server is running in the beanstalk i want it to access it as

subdomain.domain.com instead of using elasticbeanstalkend.elasticbeanstalk.com i also went through some question but as a beginner i didn't get it completely. so any helpful suggestions will helpful