To program with Arduino it is neede basic concepts about circuitry, for example who conexion in serie and in paralel work, in the voltage or the current change and in which cases.
It is important to know that when two elements in a circuit are connected in serie tha intensity that go trought both elements is the same but the voltage is diffferent. On the other hand if two elements are connected in paralel the current is different, because it is split into both paths, but the voltage that go throught both paths is the same.
Once this basic concept is understood, it is important to know that the LED's have two poles. One is the positive, which is related with the end of the LED that has more lenght, and the other one is the negative, which is realted with the short end of the LED. THis is very important because the poles of the LED must be the same than in the battery otherwise, when the battery will be connected to the LED, it won't be any response if the poles are connectedin the wrong way.
One important thing is that Arduino program some templates to make easier the programming part so it i very useful to take advantage of this templates when we are starting to get in contact with the program.
Arduino plates are very easy to use but is iimportant to know were are the inputs and the outputs, as well as knowing when is an analog input and when it is digitsl to connected to the right place.