Installing Applications

Ok peeps, I'm about to show you guys how much of a mac idiot I really am. Bear with me.

I am really not sure how to install programs on a mac. For example, when I downloaded Mozilla, it sent the .dmg file (i assume that is the standard file name for an executable file, correct?) I moved the file to my applications folder, then clicked on it. It did 'install the program', but it views the program as a drive/cd drive. I moved the Mozilla icon to the dock, but whenever i reboot, the mozilla cd drive on the desktop goes away, the mozilla icon on the doc no longer works, and I have to run setup (or whatever i am doing as setup, i am pretty sure i am doing it wrong).

Can somebody point out where i am going wrong, and a step-by-step of how correctly do it?

thanks guys, i appreciate your help.

dmg files are "disk image" files, much like inserting a CD or Disk. You first open these files which mount them onto your desktop like a cd, then drag the actual app file (application) to your application folder. That installs the program. Then you eject the mounted image file, then delete the dmg file by dragging them to the trashcan in that order. Next, drag the icon from the applications folder to your dock if you want a shortcut out there.

search the forums.