CANT GET BACK TO MAC OS

When I had originally switched over to Windows about two hours ago (to download a game unavailable for Mac OS) I was unsure of what was downloading and deleted/cancelled it. The thing downloading was bootcamp assistant and now I'm not sure if there's any way for me to get back to Mac OS? I'm stuck in windows and key commands won't work as far as I know. I've only had my Macbook for about a week and I'm unsure of how everything works. I'd hate to be stuck with this problem at a time when you can just go in to the Apple store. Any help is appreciated, thank you!