Help me about measure clock on osciloscope.

I understand, that you already did some basic timing checks with your design, as you reported it "failed at 500 MHz". The classical timing analyzer would be sufficient for this simple purpose. You can also expect, that Quartus doesn't allow assignment of "unreachable" pins or similar. In so far, only a few basic issues, that can't be checked by Quartus, may explain the said problem:

- you specified a clock input, that isn't actually connected to a DE2 clock oscillator

- you send the output to a Cyclone II pin other than connected to the expected GPIO

- you generated an output signal, that's too short to be viewed by your equipment

- you didn't manage to downlöoad the correct configuration

- your DE2 board isn't working correctly

Please apologize that I consider such basic issues, but they happen every day.