Craft Edge

I am going to start selling my homemade cards online, at home and also at fairs. Where can you get images that don't have a copyright to use? Also how much does something need to be modified in order to make it your own.

Thanks

You want to look for clipart collections that state that they are "royalty free." Also check what is called the "angel policy" for clip art to see what is allowed. You can also use public domain art such as the svgs in the online clipart library. Clker.com is the easiest way to access the OCL.
You should search some artist/legal sites for more info on copyright. Folks here are not necessarily well versed in copyright law.