usermod for first user to have/be an admin user

Just installed F17 KDE, and discouraged that editing and saving jpg files as the first (and only non-root user)
gets blocked on that firstuser desktop (where everything is getting stored).

A google search led to forum posts about how F18 may not act like this - great !

But what about F17 for now ? Giving the only user the root privileges necessary to save files on that first-users desktop
should be do-able from terminal as root.
Logging in as root user is OK but cumbersome, so how do I change permissions in terminal?

Something like . . .
... is target_account root? I dont want to make a mistake here.

Thanks in advance.