Upgrade FreePBX/Asterisk

Hi! I have resent upgrade the FreePBX to version 12. And som functions as FreePBX system statistics needs an upgrade of Asterisk. I run Asterisk version 1.815.210.58-1.
How do i upgrade the Asterisk on my installation?
I have fond this article: http://wiki.freepbx.org/display/FD/FreePBX-Distro-6.12.65
Is this how to upgrade?
Need som help on this, please!