The answer thankfully is simple. Use the PC computer name.
If pc 1 is named pc1-me
pc 2 is named pc2-other
You need to share the folder first
Create a folder.
Right click on it Sharing and Security.
To make it simple, for now, add the user everyone and give them Full Control.
You can create a new user assign a password and adjust the permission as you choose.
For testing on "pc 2" go to Start and Run type:
For a more permanent connection:
Right click on "Computer" or "My Computer" select "Map network drive"
If you setup security then you need to use: "other credentials" check box and enter them and save the username/password.
If you setup up security (username,password, and/or file permissions) you will be prompted for it now.