This was helpful, thanks! I have NO artistic ability or image design skills, but I think I can make something at least serviceable with what I learned from your video.

My takeaways:

• https://pixlr.com/express/ is a free and easy tool for making images for steemit
• it allows you to add and resize images to build up a final image
• save your images to http://imgsafe.org/ for use on steemit

That last point is something I wish I knew before I made my first post here!
I had read that steemit was eventually going to allow us to upload images here directly, and those images were going to be stored at https://ipfs.pics/ so I used that site for the images in my first post.
Warning! If you use https://ipfs.pics/ then your first image WILL NOT show up as your lead image in the post list pages!
I found this out the hard way! Now in the future, I will use http://imgsafe.org/ to store my steemit images.