Stream from hard drive connected via Windows 7

I am new to OSMC. I am set up with a Raspberry Pi 3 connected to a Windows network. I can stream media from a NAS drive on the network, but not from a hard drive attached to a Windows 7 computer. Because I can access the NAS, I believe the RPi is configured correctly, and I have tried many variations of drive and folder sharing, but cannot get past the Windows “workgroup”. Thank you.