• They both need to be in the same workgroup.
• Press Windows-key+Pause/Break button and that will pull up the computer properties, look at the WORKGROUP on both machines to make sure they're both in the same workgroup.
• Decide which one you're going to change to match the others workgroup to by clicking on Change Settings, then click the Change button, rename the workgroup to match the other computer, click okay then reboot when prompted.
• After reboot right-click on the folder you want to share and select Share With...,click Advanced Sharing, give the share a name, select the your user as having permissions, click ok.
• On the opposite computer open Windows Explorer and in the path field type \\<computer name>\<share name> and then...