You're right, it is a little bit complicated with tick value on Soybean Oil (I have experience to trade spread). My answer I simple: You need to find a trading platform which allows to trade futures calendar spread. They are expensive for beginners but has Free-trial so you can try it for study...
But my question is: how can I sell corn (blue) if I don't even own it yet?
I think you need to study the basics of trading futures. After that, you can come to trading calendar spread. Really this is the best way. Try to find in google/youtube "what is short position?" something like this.
But...