Welcome to LQ.
Here's a short howto in re the subject of changing the username. http://wiki.archlinux.org/index.php/Change_username
For future reference, if you have a question relating to GNU/Linux, direct you question first to www.google.com/linux
. Probably 99% of the questions you may want answered have already been answered. BTW, google also has similar OS specific search filters for microsoft and macos.