This is the front of the invitation. It was created using a freebie and rubber stamping the image in yellow and green. I added a text box. I then saved as a jpeg and printed 4 to a page (wallet size pic). I cut the print out and glue it to the front of a 4 * 6 inch piece of brown cardstock. You could add some more embellishments if you wish.
Above is the back of the invitation where all the important stuff is. Again I used the rubber stamping option for creating the running border and the shadow for the party title. Save as a jpeg print at a wallet size pic, cut and glue and you have created an invitation. You can embellish as you like. This would be simple to do in any graphic program. Enjoy!