I have Canon Pixma mg5420 with usb to Yosemite 10.10.2, no CD drive on iMac, don't know which driver/software needed. Thank you.

The Mac printer drivers are not included on the included CD. Just Windows.

The Mac printer driver for this model is available from Apple. So all you need to do is connect the MG to your network or directly to your Mac and then open Printers & Scanners and click the plus button to add the printer. When you select the MG5420 you will get a prompt stating that the driver is available from Apple and would you like to download and install. Agree to this and the driver will be installed automatically for you.

Also, this model supports printing via iOS devices so you also have the option of adding this printer using Apple's AirPrint driver, which is a basic driver for printing.