To do this you will need to storyboard out your game
What screens will you need to have to make an effective game?
Use the storyboard templates to draw out a storyboard for each screen in your game. Remember that the drawings need to be good enough for someone to be able to know what your level will look like
Have a look at this example from last year, to get an idea of the standard required
https://dida.wildern.org/07emily.pullen/D205SPB11/Development.html