How can I add Description editor block for downloads below upload tab.......

There is no description for downloads, only names. You can describe it shortly there.

More detailed description may be given at product details.

I want to play stream audio below the download link. 

So, i have to put html code below the link. If we use product description it will shown only in bottom of the tabs.

Is there any chance to move the description block below the download link or to  display the description below the download link..........

No, there no such ability at this moment.

Ok! No problem

Thanks.