So, when you choose "Sharing", you will see a window with tabs for "General, Tools, Hardware, Sharing". At the Sharing area, you will see that your drive - whatever letter is - proceed by a "$" sign. That means in Windows, it's hidden ( but the smart Engineers decided to leave those default to your drive letter such as C and D but how hard it's to guess that??? ). If you clicked on "New Share", it will give you a dialog box with options like ShareName; Comment;User Limit and Permission. You need to properly set that up. If you are new to this, just do a world writable and allow guess log in.