On the one hand, that's wonderful! But on the other hand, now we'll never know what /Trash was all about.
I tried an experiment. I created a DMG, moounted it, then moved it to the trash and ran Disk Utility. Disk Utility said it was in /Trash even though, in reality, there was no path called /Trash. Bug in Disk Utility, I think.
Rita, you can double-click a .dmg; just don't double-click the things IN the .dmg if they're an application rather than an installer. Drag the application to your Applications folder, then open your Applications folder and run it from there!