A prototype is a bit like your first draft in writing.
Things to do today:
Add sprites to your game: Background first: It works better in the software this way.
Rename them to something useful: Having Sprites 1,2,3,4, etc will be confusing
Begin to make your sprites move round the screen: Will the user control them? Will they move automatically?
The video below is a reminder of how to add and rename sprites.
If it doesn't play, try this link.
Break the game down into manageable chunks.
Get one bit working before worrying about the next.
Have you storyboard to hand, but it can be altered as you progress.
To see a reminder of some ways of moving a sprite, click here.