If you want to connect to the MP620 via wireless, then the instructions are stating that you need to have your wireless access point (the wireless router) ready and you need to know some information about the router, such as its SSID (its name) and any password you will need to connect to it.
The setup is pretty easy. It's just the manual tries to cover too many options.
First you must have the printer driver installed and be connected to it via USB. This is so you can communicate with the printer to configure the network (LAN) settings.
With the printer appearing in the Printer list, you can open the printer queue and select Utility. From the new window, select the Printer shown as a USB device and click the Network tab. This will guide you through connecting it to your wireless network. This is where you need to know your access point information. Once the printer is connected to your wireless network, you will be prompted to turn off the machine and then unplug the USB cable. When you turn the printer back on, you can then add the printer queue again, this time for the network connection. As others have said above, select to Add then select More Printers > Canon IJ Network. The MP620 should appear in the list, which you select and then click Add. Now you are ready to print...
PaHu