Map changing hacks

I'm not too sure on how to do this, and it's something i've seen a lot of people talk about. Apparently you can type in "change map 2" or something along those lines somewhere? I'm not too sure where to type this, and I'd like an explanation please. Thank you

bind 0 "changemap_to_next_random_sector"

or you can just type this without binding

changemap_to_next_random_sector

hope that helped

Also you can type in the command: changelevel2 and it takes you to the boss level, but it isn't recommended because your time to finish the mission would be too fast.