There are two kinds of hackers out there one is called a script kiddie, theses script kiddies use software that other real hackers have made to destroy things. if your are interested in only destroying things and being a script kiddie you can go to the pirate bay and search for anonymous tool kits on there. I would not suggest this would I would suggest growing your knowledge of how computers work and how to hack ethically and maybe even make a career out of it. The first basic thing to start with would be SQL injection. SQL injection is where someone in injects code into a database and the malicious code is executed. here is a ethical tool used for SQL injection:http://itsecteam.com/products/havij-advanced-sql-injection/
This is only for ethical purposes. I recommend you use this only if you have permission.