How to add qet123 Commands?

http://forum.ragezone.com/f245/commands-889874/

I know how to add normal commands ..
But qet123 said :
I won't copy paste the whole fucking source, just make a new packet call it whatever you want, make a server check and that's it.

If any1 can explain what he meant by "just make a new packet call it whatever you want, make a server check and that's it ", it will be helpful.