How can I change my displayed name

[Gianluca]

Hi all,
I've made a mistake during registration and I may inverted first name and last name ... so, my name is Gianluca and my last name is Massera.
I'd like to change my profile to display "Gianluca" and not "Massera" as it is now, but didn't find any option in the Profile section to change the name :-(

Can someone help me on that ?

Thanks,
Gianluca.