I can't find it. I can't run it. I have no idea what to do now that it's on my computer. I'm new at this stuff.
I went to http://www.geogebra.org/cms/en/download and selected the Web Start. Firefox asked me how I wanted to run the file and I selected Ice Tea Java (that's OpenJDK 6 in the software center).
After that it downloaded some stuff in a window and then loaded. And it put an icon on my desktop. I'm good to go.
In short: Install Java and use the web start.
Seems to me you did not extract it correctly.
Try this if you already didn't.
If you did not find any executable distribution of any kind then run
if that does not help contact me again if you will.