Your Godinterest blog comes with a free address, like example.godinterest.com. You can get rid of the .godinterest.com part and use a custom domain name instead, like example.com. Adding a domain is a paid upgrade:
Map an existing domain (one you already own) to your Godinterest blog – if you already have a domain that you registered and purchased elsewhere, but want to keep managing it via your current provider (note, you’ll still need to pay them for the renewal each year.)
You can add as many domains as you want to your blog. For example, you can add multiple domains to cover common misspellings of your primary domain, so that visitors who make a typo will still get to the right place. One of those domains will be the Primary Domain: all your other domains will redirect to the primary one. Visitors can get to your blog using any of the domains you added, but the address they see in their browser’s address bar will always be the primary domain.