baby won't stay asleep

Megan
What do you do when baby just won't stay asleep. I mean awake after 20 min of being put down. I wouldnt mind except he was up every 2 hours during the night. I'm exhausted. People say sleep when the baby sleeps but my baby won't sleep. He's in his crib just crying right now because I don't know what else to do. I have 2 other children and I need to get dinner ready and need to wash bottles. I just want to scream today!!!