Formulas in Zoho Creater

Hello Everyone

I'm new to Creator, and I'm trying to teach myself Creator, but I'm having trouble. I'm trying to create a formulator inside Creator that will subtract to dates. I tried using standard Excel logic, but it doesn't work.

Is there a "cheat sheet" that one can use to assist.

I have tried using the tutorials on the web (Youtube) , but the interface they use is outdated and looks completely different from the one I'm seeing