There's a lot of really bad, confusing info on this thread.
Here's the answer clean :
1. Doesn't matter what's wired vs wireless, they're all attached to the same house router, which is behind your modem. This means they're on the 'same internal network', and that's all that matters.
2. Make them part of the SAME windows workgroup. Google "change my workgroup". This is level 1 stuff you can handle. You can use default "workgroup" or whatever non-spaced word you want.
3. The printer must be attached to either PC via a USB cable. (If it's a network/ethernet printer, we're having a different conversation. If it's a wi-fi printer, again, different conversation).
4. On the computer with the printer attached, share it. Go to "devices and printers", find it, and turn sharing on. Give it a simple share name like "Cannon" or "HP", or "Dell" or whatever.
5. You can then to go the SECOND PC (the other non-printer hosted one), and search for printers and find it - OR you can type in the "share address" you go on the first pc (such as /david-pc/HP, etc).
There ya go.