How can I sell my greeting cards ideas online?

Have you considered cafepress for the fulfillment side of the cards along with a website designed to gather people's interest in your card ideas? Yes, there are drawbacks to this system but if the card companies don't let you present your ideas to them (very possible) then this may be the way to get started. Make enough money and you could start your own printing company.

You should start by picking up the phone and calling Hallmark, American Greetings or one of the other top greeting card manufacturers and asking them how to submit ideas online. You should also be able to ask the name of the person or people who make those decisions so you are approaching the right people. You don't want to just click on a "contact us" button of a website because I assure you that your email will go to an assistant whose job it is to hit the delete button. Every company has their own ways to purchase ideas so make sure you're using the right method for the right company. Good luck to you in your endeavor. I would suggest reading about creative property in books from your local library. They will help with the legal aspect of protecting your intellectual property rights. Your next action should be a list of greeting card manufacturers and a smile.