Press 1, 2, or 3 to load a park (on the intro screen only). Select a category from the right and an item from list on the bottom. Once you have something selected, click somewhere to place it. Press E and Q to rotate, F to offset and G to variate (if possible). An eraser is in the "terrain" category. Right click the "Save" button to save or to load your park! After importing, you need to hold R to load it again. Press R and hold S to delete the park and start over.
I started working on this in 2012 (?) to create a JPOG game in Scratch. That turned out to be a long and boring challenge, so I abandoned it. I picked it up again this month and decided that instead of finishing it as a game, I was going to create a save file system. And so I did. I'm not sure why, but the AI of the park visitors doesn't work correctly online. Oh well, it's not the focus of this project. Uploaded as a test for @dixiklo. Are you interested in finishing this project? Let @dixiklo know, please! :)