How do you count or use the function count

[ashanti]

I am a beginner in using OLAP, so please forgive my simple question.
I have data made up of one dimension and one measure.


City number
---- ------
Atlanta 1
Macon 0
Macon 1
Atlanta 1

Results:
city number
---- ------
Atlanta 2
Macon 1

I am trying to count the number of cities, which is
atlanta=2 and macon=2.

Thank you..