Sure you can learn how, all it takes is time!
First and formost, most hacks and template modifications come with good install doc's. Honestly if you know how to copy/paste and read a .txt file you can install 99% of the hacks posted on this site.
The first thing you want to do is set-up a test board, this will allow you to test modifications outside of your live communitys. You can run vBulletin on your own pc with the right software, check out this thread (
https://vborg.vbsupport.ru/showthread.php?t=39482).
Secondly you need to learn how to install a hack, here is a thread that will help you with that:
https://vborg.vbsupport.ru/showthread.php?t=39142
Also some tips to help you upgrade your hacked copy of the software:
https://vborg.vbsupport.ru/showthread.php?t=38545
https://vborg.vbsupport.ru/showthread.php?t=66860
If you want to take it to the next level and learn how to code your own hacks, check out the following sites:
www.php.net
www.mysql.org
www.sitepoint.com
Learning php is not hard, it just takes awhile to wrap your brain around all the avaiable functions and how they work and interact with each other.