Prerequisites are indicated as A -> B or
A → B to indicate prerequisites. If something has
multiple prerequisites write them down as A + B -> C.
Each line may contain multiple arrows, which will quickly describe a
sequence of powers.
When you are happy with the preview, hit the "Save Diagram!" to save your diagram. This will also produce a link to the diagram that can be used on the forum. (Alternatively, you can simply use "Save Image As..." to save the preview image to somewhere.)