setting up new me.com to activate iCloud when I already have one
You need to clarify your questions a little, but it sounds like you are trying to set up a new iCloud account directly on your iOS devices, and wanting to use your own Mobile Me account as the template (as it were).

The best way to do this, is to go to a computer and log into me.com using your Mobile Me account to verify it's still active. From there, you can move your MobileMe account to iCloud by visiting me.com/move. 

You also will want to read over two articles that discuss FAQ about the transition...


Creating an iCloud account: Frequently Asked Questions
Apple IDs and iCloud 


Once complete, you will then be able to include your iCloud details during the account setup on your iOS device, and it should just work as the existing me.com address will already be converted to an iCloud one.