Hi RichW, and welcome to the forum!
Assuming that both computers are connected to the same router, one wired and one wireless, it is definitely possible to share folders/files between the two computers. Ensure that each computer has a unique name and that both belong to the same workgroup. Next, ensure that File and Printer Sharing is enabled on both computers, right-click on the files/folders that you want to share and under the Sharing tab, click in the radio buttons beside the preferred options (eg., Full Access, Read/Write Access only, etc.).
If you need more detailed information, please post back with the operating systems that are installed on each computer.