File sharing between PC to mac

I am having trouble sharing files between my PC and Mac. I have done it before from following the instructions from aboutmacs.com.

But something happened and now I can only view my Mac through my PC and not view my PC thru my mac.

Before when I set everything up, from my mac I just had to click on the network icon, click connect and it should show my PC name, now nothing shows up when i click the network icon. Any suggestions? Thanks.