What tutorial Roger? We do not know what you are working on so please tell us more. Does this tutorial have a name or something we can use to identify the Project?. There are many tutorials showing how to code with Blocks.
Perhaps this will help. To be able to 'find' the ListPicker on the Blocks screen, t first drag the control from the Palette onto the Designer screen

only then will the ListPicker appear as a choice on the Block screen

Click on ListPicker and a drop down of the ListPicker blocks appears. Drag the appropriate block on to your Block screen.
Is that what you wanted to know?