How do I make floating sectors?

PLEASE MAY SOUND NEWIE but... I already know how to make thok barriers, unglitchy walls and diagonal parts, but I dont know how to make floating sectors... maybe someone that just discovered, but I need help, it would be thanked.

http://wiki.srb2.org/wiki/Floor_Over_Floor should have what you need to make your floor over floor. If you are not sure what the blue words mean, you can click them and it will go to another article explaining what they mean.

EDIT: This belongs in editing help. If you need help on making something for your wad, editing help is the place to ask.

Thanks torgo, that was fast.