Printing greetings cards - Canon printer

[Cardy]

Hi - I'm having a real problem aligning the images that I print on to greetings cards - they are never central, always too far off to the left (so they sit too near the fold of the card). I want this batch to have a border so I'm not yet exploring borderless which is a good job really as I have to enter a custom size and it doesn't look like borderlesss is an option when you do that. I enter the custom size via the printer driver. I have a Canon Pixima IP8750. I've downloaded My Image Garden but haven't seen anything there that is going to help me create my greetings cards. I've been creating the image in Gimp. Am I missing something?!