Activating TLS on my application server

Hello there!
Im hosting the full chirpstack Stack on an AWS virtual machine, I wish to activate TLS on my application server so I can use HTTPS protocol for the REST API.
What do I need to get the TSL certificate?
I need to have my own domain name?
How do I link the 8080 port to that domain?
There is a way to get the TSL certificate just whit an IP and a port?