To change a name or edit an email address please follow these ideas: (First of all right now you cannot edit an existing name or address, you have to delete and then add a new entry.
1) Go to your "My Account Page"
2) Find the tab at the top that says "Address Book" and click on that
3) Search for your friend's name and then delete that
4) Add the new entry on the upper right.
See attached for a visual