It is perfectly fine to learn about hacking. The more you know about it the easer it is to prevent getting hacked. 90% of hackers do it as a hobby, they will right little scripts that they plant in your computer to pop up a message or something innocent like that. the other 10% has a little more malicious intent. the main goal of hacking is to gain information that doesn't belong to you i.e. credit card info, top secret government files and so on.

the easest way to hack is to find the backdoor of the system that you are wanting to hack. on almost every OS, program or server the main adminstrator or programer will install a backdoor that bypasses all of the main security functions, so that if they need to get into the system again or need to make a change they don't have to go through the hastle of loging in and going through all the security options.

There is actually a lot to learn on this subject. i suggest looking up a few articles on it.