Duplicate post. click here
"How can the printer/cd etc still work when they aren't physically connected to the side of laptop?"
I was assuming that you meant, if the laptop was being used as it is now. If you want to move around with the laptop, then of course you would have to plug the devices in to get them to work.
The router will broadcast the wireless signal which will be picked up by the laptop's built-in wireless card (if it has one, most newish laptops do have one) or by a USB wireless network adapter click here plugged into the laptop. Normally if you're moving round the house or garden, the printer, ext CD player, etc. aren't plugged in. You can print wirelessly using a print server or a network with the printer connected and shared on another computer in the house, but that's a different question to the one you asked.