FA at a Tutorial Collage :) (Alcohol Marbling Tutorial)

I know this specific tutorial has been done on RedditLaqueristas, but I'm thinking of starting to make tutorials on a regular basis. I know this doesn't look very good and I really regret the random bunch of text or maybe just the background of it. :P Anyways, are there any good collage making programs for Macs anyone can recommend? I used Picture Collage Maker Lite for this, does anyone know if the full version is much better? Thanks! :)