How to create a greeting card from a photo in iphoto

Get the mimeo extension from the app store.

https://intercom.help/mimeo-photos/en/articles/2141632-how-do-i-start-using-mimeo-photos

Or use something like Photoshop elements or even Pages.

Go to the App Store and download one or all of the apps shown in this screenshot and give them a try to see which suites you best. They are free.

You can get free pages templates for cards online.

Paste your picture into that.