The instructions for installing toner cartridge are pretty universal. The issue that comes up for Canon users is that installing the new tank does not always reset the toner levels in the software. This is because of the chip on the replacement tank. It is highly recommended that you use only Canon brand cartridges because of this chip. Using an off brand may cause you long-term issues with your printer.
Under the scanning area, look for the drum cartridge (which is the primary ink), then pull the cartridge up and out, paying special attention to how it is seated in the machine.
While holding the green handle of the new toner, carefully place the cartridge straight down first, then pull it down toward you.
It will lock into place. Check to make sure it is aligned the same way the old one was.
Installing the new cartridge should reset the levels. If this was done properly, and you are still experiencing problems, the machine may need servicing.
Printers need to be cleaned from time to time. See your user guide for tips on maintaining your printer for optimal performance.
While most printers are reasonably durable, if you notice any loose parts, consult a professional. It is best to change toner in the morning before the machine has been running for the day. Many of the parts inside can become very hot.