Before anything, you need to purchase one domain with a provider of your choice (GoDaddy, Bluehost, iPage, HostGator, etc).
Once you got your domain you can choose if want to host your site from your own CloudFlare account or if we do it from ours.
If want to manage your site please take a look at this article: http://help.ordering.co/getting-started/manage-my-custom-domain
If want to us manage your site please fill this form: https://www.ordering.co/domain-change/. This form helps us to add you site to our CloudFlare account and in that way your site can load our page.
If you're having troubles changing the domain records just mark the "I don't know please help me" answer in the form and we'll take care of that. Also, you can search for the documentation or contact to the support of your provider to guide through that.
Documentation that might help you:
After this you need to add your domain to your builder, for example if your domain is mydomain.com then you need to add www.mydomain.com to your builder like in this example. Then remember to save changes and rebuild.
After doing this, then you only need to wait up to 48 hrs due to propagation time.
Glad we can help.
Have a nice day
Regards, Pol Zepeda