The basic structure of a program is given by the following two Kniwwelino blocks :

Kniwwelino on start contains the blocks which are only executed once, at the start of Kniwwelino (for instance the variables initialisation).

Kniwwelino repeat forever contains the blocks which are executed repeatedly, while Kniwwelino is powered.

To compose your program, you need to connect one after the other. Drag and drop the blocks to connect them. As soon as you see a yellow mark, you can connect them.