I am a senior citizen and brand new to computers and the computer world. I was given a Canon iP1800 printer .?

I d not know how to load the ink cartridges into it. My grand daughter put the ink cartridges in for me when she came by the other night.However when I tried to use the printer it says cartridges are loaded wrong. She is 100% sure she loaded it right. Can someone please tell me what would be causing that message .This is my very first time using a printer. Should I have done something when the printer was hooked up to the computer? The computer is a brand new HP computer HP Omni100PC. It is a new kind that does not even have a tower. PLEASE HELP ME IF U CAN. I am brand new to the computer world so please explain in real simple to understand terms Thank You