I'm not sure what all of them mean. Does it come with a manual?

and I'm trying to figure out how to make the "land" portion a little bigger

In the panel where you apply textures to the terrain, there is terrain size

For help i would suggest clicking on the ? icon top left

and our reddit has some tips

https://www.reddit.com/r/FlowScape/comments/aq6j6u/flowscape_tutorials_tips_and_tricks/

hope that helps