If you have registered a new domain it can take up to 24 hours until it can be accessed by everyone.
When a domain is registered, it can be compared to creating an entry in a phone book. This entry is called a DNS zone. The internet has thousands of DNS servers (called nameservers) around the world which hold copies of all the world's DNS zones. When you type a website address into your browser, your browser will then contact a DNS server to obtain the associated IP address which is like a phone number for a server (which is just a computer that has your website and e-mails on it).
When a new domain is registered with us we create a DNS Zone instantly on our nameservers. However it takes a while for all other nameservers around the world to also update your new domain, and the time it takes can be different for everyone. So even though you might be able to access your domain after just 30 minutes for someone else it might take several hours.