recording age into different variables

Hi,
I am new to R, I would like to know how i can summarize age data into
different categories i.e.
Age
14
16
20
60
45
.
.
I would like to generate a summary for example showing the frequencies in
each custom defined group
0-10 yrs  11-20 years 21-30 years
20             5               6

many thanks
Andrew