To avoid needing to remember an IP, this guide will help to link your domain name to your server. It assumes you have already attained a domain name.
Login to your domain name registrar
Login to the registrar, and select the domain name you want to point at your server.
Find the section for DNS
The domain name should have a section named, "DNS", "Custom DNS records", or something similar to this. Find, and open it, there should be a bunch of boxes and an option to add a new record.
Add the A record
Find the box that allows you to "Add a new record" and input the below, changing
<DOMAIN> A 86400 <IP>
Wait for propagation
Now there's a bit of a waiting game, as you need to wait for the new DNS record to propagate (get updated) for all nameservers. This can be anywhere from instantly to 72 hours, but typically takes an hour or two.
Check your domain has propagated
Pinging the domain name will let you know when the IP has propagated, as when the ping command shows your IP, you're all set.
ping -c 3 domainname.com