Automatically rearranging text in a cell
 

I have a spreadsheet listing names of people. I copy/paste the full name of
the person from another program into my spreadsheet, but my problem is that I
then need to display it with the Surname first. eg: if the name is "Joe
Smith", I want it to display as "Smith, Joe". Is there a Macro or something
that can automate this process for me? I'm new to Macros and couldn't get one
to work properly.

Thanks in advance!