To clarify, the keyboard commands given above are run within the GeoGebra application, not the web browser. I am using GeoGebra Classic 5; I'm not certain if they kept the same commands in other versions.
(I find the input bar in GeoGebra 6 hard to use. In GeoGebra 5, I can enter a polynomial like x^2+3x+2 as you would in WeBWorK. In GeoGebra 6, once you've typed x^2, the cursor moves up to the exponent, and stays there until you use a right arrow key to move back down. I guess this is for students who don't believe in parentheses.)