I'm sorry for asking such a stupid question. Up until now I've only used fondant to decorate my cupcakes.

I'm wondering if someone can help me with a recipe for sugar icing on my cupcakes? It should be firm/hard after decoration because I will need to box it up.

Thank you so much!

Sounds like any crusting American b/c should work well for you.

Here are some highly rated CC American b/c recipes:

http://www.cakecentral.com/cake_recipe-2375-Brite-White-Buttercream-Icing.html

http://www.cakecentral.com/cake_recipe-5163-Sugarshacks-icing-and-Tips.html

http://www.cakecentral.com/cake_recipe-6992-Indydebis-Crisco-Based-Buttercream-Icing.html

http://www.cakecentral.com/cake_recipe-7300-High-Ratio-Sweetex-Frosting.html

http://www.cakecentral.com/cake_recipe-7215-Foolproof-Crusting-Buttercream.html

http://www.cakecentral.com/cake_recipe-7378-3-Cakepros-Buttercream-with-Trans-Fat-Free-Crisco.html

Here's a HUGE cupcake thread:
(That has recipes.)

http://www.cakecentral.com/cake-decorating-ftopict-582525-.html

HTH