creating jet reports

i think it would not be relevant to write this post here bt i need a help for creating a report in jet express. i have "age" field in the vendor table and i want to utilise it in a report and bring the data as per the age group. for that i need to keep a range of age from supose 10 - 20, 20 - 30 , 30 - 40 and the number of vendors must be totalled ..need help