Does your router support wifi or is it strictly a wired router? If you don't know the answer to that question then post the make and model of your router and someone should be able to tell you.
What is the make and model of your printer? Some support wifi while others don't. If the printer doesn't include wireless support, it can still be done with the addition of a wireless print server which would cost $35-50 or so.
I personally use my laptops (and tablets) wirelessly with my printer, router and modem so it certainly can be done.