[ubuntu] Where do programs install by default and how do I change that location?

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http://ubuntuforums.org – I just downloaded Skype, my first time downloading a program which was not included with the Ubuntu package. Once downloaded I was taken to the Software Center, which prompted me to press Install. I did so. It installs. It works. And I have no idea where it is. I cannot find it under the Home folder nor in my perusal through the drive. I also apparently cannot right-click to access Properties like in windows (do things have properties in Ubuntu?). Any and all help would be appreciated. If you can't tell, I'm very much a noob; I just installed Ubuntu about an hour ago. So if there's s (Hardware)