If you want to use an exisitng domain of yours as part of your 1uhost.com order rather than register a new one you simply need to select transfer on the domain page when placing your order and enter your domain. Then process your order as normal and once you have received your confirmation email you can point your nameservers to YourHosting. The details of the nameservers will be provided on the welcome email of 1uhost.com while you signup.
The changing of nameservers may take up to 48 hours.
For further information on transferring from different hosts or if you need any help regarding the transfer please contact us at support@1uhost.com .