How to Hack a website

First find a Vulnerable Website?

Common Methods used for Website Hacking
There are lots of methods that can be used to hack a website but most common ones are as follows:

1.SQL Injection
2.XSS(Cross Site Scripting)
3.Remote File Inclusion(RFI)
4.Directory Traversal attack
5.Local File inclusion(LFI)
6.DDOS attack

Tools:
Acunetix:
Acunetix is one of my favorite tool to find a venerability in any web application It automatically checks your web applications for SQL Injection, XSS & other web vulnerabilities.

Nessus:
Nessus is the best unix venerability testing tool and among the best to run on windows. Key features of this software include Remote and local file security checks a client/server architecture with a GTK graphical interface etc.

Retina:
Retina is another Vulnerability Assessment tool,It scans all the hosts on a network and report on any vulnerabilities found.

Metasploit Framework:
The Metasploit Framework is the open source penetration testing framework with the world's largest database of public and tested exploits.