I made them in photoshop. The cinderella one is a piece of the wallpaper that disney is giving out for the dvd release.
The 2nd one is a 3 hour t-shirt design I made for someone. Had to collect all the clipart art and arrange it and then I changed the words for the envelopes
The 3rd one is all part of the tshirt designing spree I went on that all started with the dwarfs (see the tshirt thread)
And the 4th one I made the circle and confetti and then looked for a cute clipart to put in it....which just so happened to be minnie mouse
I setup the envelope size in my printer properties and then when I printed I checked off "Scale to fit media". I'm not sure if you have the same properties on your printer.
You can also try doing it in microsoft word or another word processor. Also Windows XP has a built in photo printing wizard - if you save the file to your computer and then open it and choose the little printer icon.