Most times, just dragging an application to the trash and emptying it gets rid of it (most apps don't spread files all over your system). Once in a while, i.e., an app that comes with an actual Installer program, because it's not just a drag-n-drop procedure, will also have an Uninstaller option. You find it by running the Installer again and clicking the "Easy Install" button to reveal "Uninistall."

Those .dmg files are disk images. Once you have installed the programs they contain to your Applications folder (either drag-n-drop or an Installer), you can safely trash the .dmg. Edit I wouldn't worry about Terminal until you become a lot more familiar with your Mac. It runs outside the OS X shell in straight Unix and can be daunting.

G

Before you trash the dmg files, are you sure that you actually installed the software that they contain? I only ask this because you did not seem to know what they were and, therefore, may only thing that you have installed the software they contained. They can be a bit confusing if you have never worked with disc images. Double clicking on a disk image does not install the software that it contains. Double clicking simply tells the Finder to mount the image. What this does is open a virtual disk that contains the data. You then open that virtual disk and do whatever it is that you need to do next to install the software (drag the folder and/or application it contains to the hard drive or run the installer), Once you have done this, you can then "eject" the virtual disk and delete the dmg file.

Personally, I prefer to keep installers just in case something goes wrong and I have to re-install the program. If this situation should arise, then I don't have to got through the hassle of downloading the installer again. For example, last fall my Mother bought a TiBook. It came with a less than current version of Jaguar on it. So, I had to update her to 10.2.8. There were three aspects of this that made this really problematic. Fist of all the update is over 100 MB. Second, we only had a dial-up connection to the internet. Third the ISP kept disconnecting before we could get the entire update downloaded. I wound up have to pay one of the local Mac dealers to download the update and burn it to a CD for me. Had I kept the update from when I downloaded it to install on my own Mac, then I could have save myself quite a bit of aggravation. (At the time that I updated my computer I had a broadband connection. So, downloading the update was not a problem then.)