If you are interested in Ethical Hacking and the IT Security area in general, you should know how to use the Kali linux distribution.
It provides the best tools and it is currently a market standard (if you work on IT Security, they might expect you to know how to use this distro, even though using the tools and more technical knowledge is more important).
There are many tutorials and books available online and elsewhere on technical subjects and How-to's to learn Kali and its tools.
The link for download this distro: http://www.kali.org/
