Graphic Design Help

Anytime I want to get an invitation for something, I go on Etsy to buy something. I have always wanted to learn how to make them on my own though. I have absolutely no idea where to begin. I've already graduated college and got an additional license as an appraiser. I'm not interested in getting a graphic design degree. I wouldn't mind learning the basics though to see if I can tackle it and create a new hobby. Any advice on programs to use to get started?