Mix cream cheese, onions, crab, and sugar together in a bowl.
Put about one TBSP of the mixture into the middle of a won ton wrapper and fold the wrapper up around the cream cheese mixture. (Folding doesn't matter as long as the wrapper is around the cream cheese mix).
Continue to do this until the all the cream cheese mixtures is used and then put them on a slightly greased baking sheet.
Bake at 350F for about 12 minutes or until the corners of the won ton wrappers turn brown. I always check them at about 8 and 10 minutes or so, just to make sure.