Help Please. New to mac, question about location of downloaded applications

I first downloaded google earth application to try out and mess around with. Nice app! I then downloaded mpeg stream-clip application. Both applications worked great after I download them. I shutdown my macbook pro over the weekend while I was out of town. First time I have shut it down since purchasing it. I could not locate these applications after I booted up my macbook pro today. After looking extensively for the apps, I found them in my download folder. I thought these apps would be located in my application folder???? Did I miss something??? Do I need to drag .dmg files to my apps folder?? Thanks in advance!!!