Option 1
Connect both computers to the same WiFi router.
Enable File and Printer Sharing on both computers. If you right click on a file or folder from either computer and choose to Share it, you will be prompted to turn on File and Printer Sharing.
View the Available Network computers from either computer.
Option 2 - App
FileSprint - a simple highly-performant WiFi file transfer app which requires only one person to have the app and every one on the local network whether on mobile or PC will be able to share files with one another