Yes you can, all you need to do is change the nameserver for your domain at your registrar, then the Internet know that your domain is hosted on our servers. The first step is going to our hosting plan comparison and choose a hosting plan. Then follow the steps to the order form, select 'I already have a domain' . Note this will not transfer your domain from your current registrar where you registered the domain, this will only transfer the hosting if it is already hosted.
After you have signed up for the hosting you will receive a welcome email with all your login information to the server. You MUST also login into your domain control panel wherever you registered the domain and modify the NAMESERVERS or DNS to ours, your website won't be live until you change your nameservers.