There are many different free QR Code creators out there. Some have fees to upgrade to different levels. You can use these directions on qrstuff.com or modify the directions to use a different QR Code creation site. When you search for free QR Code creator, the qrstuff.com site is generally first or second on the list.
This year, we are having our students create simple messages for our 'Back to School' night using either qrstuff.com or vocaroo.com. When parents arrive, they are going to scan the codes located at their students cubby or locker to retrieve the message.