Visit "Settings > Domain".
How it works
Custom domains let you host your GivenGain site with a URL like "www.mywebsite.com". This can be tricky to set up, and is only recommended for advanced users. You have to already own a domain before you add your domain. You then have to create a CNAME record for it to point to www.givengain.com.
About your domain and DNS
If you do not yet have your own domain, you will first need to register it. There are many different registrars where you can register domain names, and you only need to get the domain name - no need to pay extra for hosting services.
DNS stands for Domain Name System. If you already have a domain name, you now have to tell the servers on the internet where to point it. To do this, you will need to create a CNAME record for your domain with the DNS, associating your domain with www.givengain.com. If you do not know how to do this, ask your registrar directly. Once you've updated your DNS settings, it will take a few days for the information to be transferred to all the other servers on the internet.