Adding BBcodes to existing index.php

[blind-eddie]

I have many sites, not all vb. One in particular is html. I added a guest book (PHP) to it, simple enough, but I would like to allow bbcodes. How would I go about adding bbcodes to an existing index.php? Please view text doc of code. Thanks

[nico_swd]

http://www.phpclasses.org/browse/package/2532.html
http://www.phpclasses.org/browse/package/2867.html

[Dismounted]

<a href="https://vborg.vbsupport.ru/showthread.php?t=82693" target="_blank">https://vborg.vbsupport.ru/showthread.php?t=82693</a>