* Read books discussing TCP/IP networking.
* Hackers are those that built the internet, made Linux, and work on open source software. It is advisable to look into hacking, as it is respected and requires a lot of professional knowledge to do anything serious in real environments.
* Although it's great there are many legal, safe training grounds available for anyone, there is a sad truth that you won't become any near "medicore" if you won't start doing illegal actions. You can't become anyone if you won't find real problems on real systems, with the real risk of getting caught. Keep that in mind.
* Find information online related to hacking, or to even attend an "underground" hacking event, visit these sites:
o enigmagroup.org A legal and safe network security resource where users test their hacking skills on various challenges and learn about hacking and network security. Also provided are articles, comprehensive and active forums, and guides and tutorials.
o insecure.org Hacking tools and other software.
o  Learn to hack, keep yourself safe, and many other useful computer skills.
o securityforest.com Tools, papers, exploits, and other reference material.
o Attend college and start a career in software, to learn the most about hacking.
You can do this with Command Prompt, but unfortunately, nowadays PCs or LAPTOPs are fully secured.
If you know their IP address.. firstly ping to that address...if you get reply then
use telnet to establish connection with that system...enter user name and passwd and you are in...
else go to run
type mstsc and then enter ip address
enter user name and password and you are in..