Help needed with Network Drive Problem

[stigslim]

Hi everybody, i recently plugged an external HDD into my router via a USB socket to use the drive as shared storage for all computers on my home network. Formated the drive plugged it in and all went reasonably well. I can see the drive on all the devices i have tried and all can access content at a slow but useable speed.The problem i have is copying to the drive when i get (You need permissions to perform this action). For some extra info most machines are running Win 7 and the drive in question is a Seagate Freeagent Desktop plugged via USB into a BT Homehub (for all thos that know what one is). Seems like a simple fix if i only knew what i was doing . Thanks for any help in advance.

[stigslim]

Sorry (double post) , Have seen many tutorials on changing permissions online allthough not completely understood i get the idea but i still keep getting access denied when trying to change them?. Again sorry for the double post but i just dont know what to try next .