Change User Name

[TraumaTurtle]

I bought my Mac off of a friend and I was wondering how I/if I can change a user name. I have made a user profile and work under that name...HOWEVER when i open up the User file, that name isn't there, it's actually my friend's old name. how can I get it to by my user name? I am signed up as the administrator and up in the upper right corner (next to spotlight) it says the name that I want, but when I look in the directory, the user profile is my friends' not mine. Is it possible to change it to my User name?

 

[GGJstudios]

Mac OS X v10.6 and earlier: How to change user account name or home directory name

 

[TraumaTurtle]

I'm actually running Lion. Does that make a difference?

Also, I followed the steps suggested and the field in which I would change the name is actually grayed out, so i can't change anything