Your game is tied to this Steam account and cannot be re-registered to a different account. Once you have installed the Steam application, you will need to login to the Steam account you have added (or will add) your game to. Changing the name that is visible to other players requires editing your profile which is pretty simple process. It is relatively easy to change your username that is visible to other players, but, changing the Account Name is not possible.
Keep this in mind when creating your account. Your player name can be changed at any time however, in your Steam Community settings, under 'Edit my SteamID page'. Your SteamID and Steam Account Name can not be changed, even by Steam Support staff members.
