How can I change my server name on CPanel?

Hi all, can anyone help me or give me some suggestions, please?

Please sorry for my poor English.
I want to ask about my problem on the 'server name'. I have previously had own Domain and now
I have changed with the New Hosting, and all files on the Old Hosting previously is no longer needed.
So, on this new hosting, I will be required to change the server name, how..?

I cannot seen the menus on CPanel to point how can I change my old name servers to a new name servers.
Description on detail step by step will be more appreciated, cause I'm really newbie in this case.

A great thanks in advanve for anyone to solve my problem.

 

Ouw Yes..just remember, and thank you for reminding me to have contact the Domain that I first purchase/registrar.
Sorry, I'm too focus on my problem in the new hosting, so that the first thing is forgotten. Also I've puzzled
where the Admin of the new Host said that I must change the old name servers to their new name servers in CPanel.

Once again, Thanks a ton arunsv84, my site is now running smoothly with show normal accordingly.