How can I teach my toddler to clean up the messes he makes?

If this happens every day, I wouldn't let him have a full bowl of snacks throughout the house anymore. Leave his food on the table, and he can sit in a chair when he wants to eat. If he continues to spill it even at the table, then you'll have to hand him one piece of food at a time (one Cheerio, one blueberry, etc.) until he can learn not to spill them.