When installing the 6.35 PRO-B CFW on the Psp 3000?

MY psp is well at 5.03 gen-C (so i guess that would make me OFW 5.03) it says to update it to OFW 6.25,but wouldn't that brick the psp ? Also can u tell me the steps i should take to get to the 6.25OFW?