Stuck in youtube screen -no back button ???

I'm new to Apple, just got an Ipad I got into the Youtube section and can't figure how to get back to the main screen! There's no back button. Just videos and it says "featured" "top rated" and "history" on the bottom. Yeah I realize this makes me look extremely stupid. No mattter which section I go into, there's no way to get out of the screen and back to the screen with all the apps on it. Help?