If your kids are constantly getting out of bed when you try to put them to sleep, it can be very annoying. Usually when kids get out of bed it's because they want attention. The way to keep them in bed is to not give them the attention they want. When they get out of bed, pick them up and put them back in bed without talking to them. Don't get mad at them, don't scream at them, don't tell them to stop whatever it is they are doing. Just pick them up (which can be difficult if they are kicking and screaming) and put them back in bed. When they get out, do it again. The first night of this will be tiresome as they will likely repeatedly keep getting out. But eventually they will figure out that this is not fun for them, and they will stop.

If they are of an age where they can understand you, tell them ahead of time you'll be using this technique to get them to stay in bed. They'll test the boundaries, but they'll eventually tire of the game and go to bed and stay there.