How do I edit a video seamlessly?

Im trying to make a youtube video. And there's parts where I want to get into a different outfit. But I don't want peoplto seems change, or I have to run off somewhere. I've seen people make videos, turn their camera off, & it still be in the video. Does anyone get what I'm saying? Pretty much I'm asking; how do I make different scenes in a video, where I can change outfits and upload it to youtube, & make it look like I didnt turn it off.

pause button will help... but I guess you have to be pretty quick in between.