In regular Sorry!, you shuffle the deck, you turn up a card, and you do what the card says. The game is playing you.
Modern versions (and possibly classic versions too, but I haven't seen one in a long while) have adult rules where you get a hand of 5 cards. But I've found that 3 cards is about the most that tiny hands can reasonably hold. We also allow a player who cannot use any of his cards to discard 1 or 2 cards and draw back up to help minimize the time you are stuck. Playing a 2 lets you move 2, draw a card and take another turn (i.e. just like if you had turned up a 2 in the regular game).