@trachanh,
bitshare to bitshare is not allowed as per my knowledge.. to remote upload from other files hostings to bitshare, you should have premium account of the other hostings..

ie. to remote upload from rapidshare to bitshare, if you have rapidshare premium account enter the url like following

http://username:password@www.rapidsh...m/filename.rar

just exchange username & password in links with your rapidshare premium account infos..