I found this great recipe for Fizzing Sherbert and decided to post it on this site. It is great and just like the real thing.

Fizzing Sherbet

1 cup icing sugar
1 tsp baking soda
1 tsp citric acid
1 tsp tartaric acid
1/2 tsp lemon or other essence or
2 tablesp fruit drink powder
Combine all ingredients so they are well mixed using a food processor or a fine sieve.

Also, I made sherbert cones as follows:
Place 1 - 2 teas sherbet in the bottom of an ice cream cone, fill with home made marshmallow and top with sprinkles or 100's and 1000's. Kids love them (and so do adults).