Cleaning the Print Head on a Canon Printer is quite an easy task. Most of the Canon Printers have a 'removable Print Head' as seen in the video below. Simply remove your inkjet cartridges and then unclip the print head as shown in the video below. Next simply flush the print head out under your hot water tap.
Don't pay too much attention to the guy in the video as its mainly there to demonstrate how the print head is removed. Hold the print head upright (same as it sits in the printer) and let the hot water pour into the head until you see the old ink flowing out the bottom of the print head. Keep the water flowing until the water coming out the bottom is completely clean.
Once it is fully clear then make sure that the print head is dry before installing. This can best be done using a hair dryer. Next attach the ribbon cable (where applicable) and re-install the print head. You may find after cleaning that it takes a while for the ink to flow again. Simply keep printing until the ink flows freely through the head. Happy Printing!