Creating vB modifications for beginners

[powerful_rogue]

Thanks everyone.

I found an old mod yesterday and started having a play around with it. I managed to update it slightly using javascript code from the intertnet, but then had to stop when features such as the one below stopped working and I couldnt get my head around the code to resolve it.

PHP Code:

if ($vbulletin->userinfo[lastactivity] > 0 AND $vbulletin->userinfo[lastactivity] > mktime (date("H")-$vbulletin->options[dynamic_pop_freq], date("i"), date("s"), date("m"), date("d"), date("Y")))     //popup once in every XX hours 


I went to the library yesterday, but had no php/sql books in, so I got "Javascript for the World Wide Web"

Ive been trying to find out the best php/sql book to get. Ive had a search around and this book seems to come highly recommended. "Build you own database driven website using PHP and MySQL by Kevin Yank" Even one the coders of vbulletin was reading it back in 2002, so cant be that bad!

Just wondered if anyone else had any recommendations that helped them along and managed to code mods for vbulletin after.

One more quick question, once you have a basic understanding of php and mysql, is it difficult combining it with vbulletin?