I currently have a client who had 2 domain names...the main one being popstopshoponline.com...this is where all his files are, database etc....he lost this name and let it expire. So, now I simply want to put his "popstopshop.net" domain in place of the other one, and for the life of me, can't figure out how to make this ...what would seem... easy switch. Please help. The clients website is down, and they of course are yelling at me for it. I've screen shotted what I am currently looking at in plesk on my end so if u can just tell me what button to push, I would be forever grateful. :)

wedosites.com/pops.html

Are you looking to change a client's domain name? If so do as follows
Click on the particular domain, then click domain administrator, I believe it is the very first text field. Change that, and you should be set.

OMG, I can't believe it was that easy! I can't thank you enough. I even called tech support where I have my server located and they said "uhmm...I don't think you can do that" WOW! :)

You are always welcome :)