How to set up web app on EC2?

I am trying to setup question2answer website on Amazon AWS EC2 servers. I am not exactly sure how to setup the website and get it running on the EC2 server.

Especially how to deal with the IP configuration since when setting up the website on my local Ubuntu system, it runs on localhost. Could someone please guide me with this process as it's my first time working with EC2 servers.

Also, I would like to keep the website running from there even after I drop the SSH connection.