There is no syntax to learn, indeed, it is built on top of a visual programming engine: You just use drag and drop!
To create formulas, you will use the built in base functions provided by the DragNMath library (trigonometry, logarithm …). To these built in functions, you can add yours with as many arguments as needed and you can even define them using your own functions!
The blackboard variables are very powerful. They are not restricted to numeric values, they also can be defined as a formula. Therefore, they can contain the result of an intermediate calculation that can be used in other formulas.
You formulas will definitely need some data to feed them. There are various ways to do that in DragNMath, the most common is to add Inputs. You can add as many Inputs as you want, edit their name, give them a value and drop them to feed formulas!