Arms22 wrote:i want to start hacking, but the problem is i dont really know where to start.
what should i study first?
by the way i know nothing
I'm assuming that you want to know about old school hacking and not cracking.
It would be good for you to go by instructables.com and check some of the many project areas. Do some reading there on projects that catch your eye. They have quite a number of really good projects. Once you have an idea for an area that you are interested in, google for "basic" information on the subject. You can find tons of information that's not of much use if you don't have the fundamental knowledge to safely use it.
It's not an overnight process. Just keep in mind that hacking isn't a destination, it's following a path with complete with dead-ends and even side streets that might entice you towards a different direction. But it's all good. Even the dead ends help you learn. I've been tinkering for over 50 years. Electricity, electronics, TV/radio repair, ham radio, guns, computers, programming, CAD, microcontrollers, robotics, lasers, cabinetry, metal working, wood turning, 3d printing....
Just start walking. You may never reach the end, but getting there ins darned interesting.
There are plenty of on-line sources of information, but don't ignore your local public library, either. A book is a handy tool that you can take anywhere.