You have to tell us what the problem is - otherwise nobody can really help you. What exactly did you do, and what is happening? You need to describe exactly what you see on screen (any error messages)? And if we cannot work things out here, you can contact Greenfoot Support: http://www.greenfoot.org/support

When i simply click on the shortcut icon of greenfoot which came to my desktop after installation,it is not responding.Just asking you want to allow changes and i say yes then nothing happens.

It is possible that no debuglog was written yet, because Greenfoot did not start at all. What exactly does the message say that asks you about allowing changes? What changes?

Just write to greenfoot support and describe your problem. (You'll probably have to wait at least until tomorrow, though -- it's currently night in the UK.)