How to Set up an External Hard Drive on a Network for a Mac & PC
- 1). Connect the external hard drive to your Windows-based machine.
- 2). Click "Start" and "Computer."
- 3). Right-click the external hard drive letter and select "Share With." Click "Advanced Sharing."
- 4). Check the "Share This Folder" box. Click "Permissions" to fine-tune exactly which computers and groups on your network have access to your shared drive. Click "OK," "Apply" and "OK." The shared drive is now accessible to both your Windows and your Mac computer on the network.
Source...