I have created a self-signed certificate for the domain I bought, my application is hosted in aws and I am able to point nameservers to the domain.
Next I wanted to add ssl feature in my domain, I am not aware of how this process work.
How do I add my the ssl certificate which is self signed one to the domain I bought from a domain registrar (namecheap) and application is hosted in AWS?
You have a couple of things to do to get this working:
You'll need to configure your application in your EC2 instance with the self signed certificate.
You'll need to confirm that your EC2 has a public IP that you can point your nameservers to: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-instance-addressing.html#concepts-public-addresses
You'll need to setup access from the internet to the ec2 for whichever port your application is running. Instructions on how to use a security group to grant this access are here: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/authorizing-access-to-an-instance.html (in your case the source IP would probably be 0.0.0.0/0 (ie everyone in the world) unless you want to grant that access to specific IPs as part of your testing?). If your EC2 is part of a VPC, you'll need to make sure your route tables are setup to allow internet access too along with a Internet Gateway in the VPC (https://docs.aws.amazon.com/vpc/latest/userguide/VPC_Internet_Gateway.html)
All that said, without understanding your particular use case, this isn't how I'd do this - I'd be using a load balancer and hosting the certificate in ACM while utilising it in the load balancer: https://aws.amazon.com/elasticloadbalancing/
