Hi,
Your account's main domain must be an x10Hosting subdomain, so you would need to add your domain as a Parked Domain. This is where your domain displays exactly the same content as your x10host.com subdomain, which points at "public_html". Your website visitors will not see your "x10host.com" domain (so there are no nasty redirects), and your parked domain would behave the same as a main domain would. It's very common for people to want to use their own domain, and adding it as a Parked Domain (after setting our nameservers) is usually the best option.
Please let us know if you have any further questions.
Thank you,