It is important to understand that domain names are not "owned" in the traditional sense; more accurately, domain names are leased to a person for a specific period of time.

If the domain's owner (registrant) decides to allow it to expire, the domain name is deleted and becomes available for re-registration as a completely new domain name.

Because domain names have no "memory" of who owned them previously, registrants run the risk of losing their domain names if they are allowed to expire. The registrant loses all rights to the domain once it expires; it rightfully belongs to the new owner, and the old owner has no claim over it. (While it is possible to open a trademark dispute with ICANN, it is a costly, lengthy process that has no guarantee of returning the domain to the initial owner.)

You need to Follow Following Steps to Register Your Domain:

• Go to Your Control Panel By Logging In.
• Go to Domains->Check Domain Availability

from this link you can check availability of domain by writing you domain name and selecting extension for your domain. 

• After checking domain availability User can add domain to cart
  
• if user is a Reseller he/she need to enter their Customers User Name if he/she is a Customer only need to enter their own User Name.
  
• On continuing you just need to proceed and then execute your order your domain will register.