Are you talking about using a domain name instead of the IP address?
If so you buy a domain name, which you can get for less than $10 a year. Once you have purchased one, you log into the site that you purchased it from. There you will probably find some sort of DNS control panel, which you will add a DNS record that maps

to a specific IP address. There you will enter your server's IP address, and after the DNS record gets updated, users around the world will be able to access your site via the url instead of having to use the IP address directly.