upgrade Android 2.2 to 2.2.3 on NEXUS 1 - HELP PLEASE

[ScarofScorn]

ive got a Nexus One phone with the android 2.2 and build number FRF50
how can i upgrade it to the new 2.2.3 ?
i understood i have to upgrade it to higher build before that?
im kinda new to the android
so please....

PLEASE HELP ME!