Usually, click on a file or a folder and command-i and modify privileges.
Batchmod works OK for me:
http://www.macupdate.com/info.php/id/6440/batchmodUptowner: (I haven't used this one)
http://www.macupdate.com/info.php/id/9572/uptownerChop: (rather old)
http://www.macupdate.com/info.php/id/12865/chopOr Terminal command:
http://forums.macrumors.com/showthread.php?t=8462But the file located somewhere over the network, you'd have to ask the owner or go to owner's computer to change the access privileges, I'm afraid..... please correct me if I'm wrong.
Y