1. Yes you can share a folder over the network using the Samba protocol. It sounds like you are using a PC, which is outside of my area of expertise, but google Samba sharing on a PC and you can find a good tutorial.
2. You need to get a powered USB hub to plug in more than two devices. This one has worked very well for me: http://amzn.to/13t8D5z

Good luck tinkering!

farkash7 said

No one helped me so I edit my post and ask a few simple questions:
1. Is it possible to share a folder in my computer with my PI? Example share my computer music folder, "d:\Music", with my PI?
2. If the answer to the question above is "NO" how i suppose to connect external hard drive to my PI?
The PI has 2 USB ports, one is held by my WIFI adapter, and the other by my DAC, I don't have another USB port for external hard drive.
The SD-Card is not a solution, large capacity SD-Cards cost allot comparing to regular external HDD's.
What is the solution for this problem?
Thank you