Specialty grain percentages

I've been trying to help out a friend who is a beginning brewer. He's an all grain brewer who has just started making his own recipes. He's having trouble with figuring out how much specialty grains to use. I was wondering if there was a table or something on the net or in a book somewhere that helps you learn what percentage of a specialty grain no to go over when building a recipe. The last beer he made he used 2 lb carapils 2 lbs crystal 40 and 10 lbs 2 row. That's it! Tasted pretty bad, can you help me help him?

Briess has some of that info in pdf files, Weyermann has one too.