All available operators, functions and function blocks are listed in the bottom/right area of the editor. The list of available blocks is sorted into categories.
The (All) category enables you to see the complete list of available blocks. The "(Recent)" category contains the last used blocks. The "(Project)" category lists all UDFBs and sub-programs declared in the project.
To insert a block in a program, simply select it in the list and drag it with the mouse to the wished position in the edited text or diagram.
Press the F1 key when a block is selected to have help about its function, input and output pins. In selection mode, you also can double click the mouse on a block of the diagram to change its type, and set the number of input pins if the block can be extended.