I'm sorry about the issue. Is this a new printer or new computer, etc.?
Can you please click on the Apple logo / menu, then click on About this Mac, then tell me your Mac OS X version?
Have you tried installing any printer driver / software yet?
Please reply at the box below. Thank you.
Can you please click on the Canon website below:
, then there, click on the option SELECT on the right of the item MG2900 series Full Driver & Software Package (OS X)
, then check the box "I have read and agree to the terms"
, then click on option DOWNLOAD to download and install the printer's driver / software.
When you are available, please reply at the box below to continue troubleshooting. Thank you.