You need to login to your domain registrar account and change the settings under your current nameservers.
If your registrar is GoDaddy, log in to your account from www.godaddy.com. From the menu select Domains > My Domain Names, then select your domain and on the right you'll see "Nameservers Summary" (near the bottom). There's a link "Click here to see details or to modify." - you click that and then replace the existing nameservers with what you got.
Again, we need you to configure the DNS to point to
NameServer 1: ns1.softlayer.com
NameServer 2: ns2.softlayer.com
Let us know if you need further help :)