software

Hello, I can figure this out and need some help please. I have a chart
of figures below...

A B c
JAN07 Jan 06 1200
JAN14 Jan 06 1300
JAN21 Jan 06 1670
JAN28 Jan 06 1050
FEB04 Feb 06 1400
FEB11 Feb 06 1670
FEB18 Feb 06 1090
FEB25 Feb 06 1500
MAR04 Mar 06 1700
MAR11 Mar 06 1900
MAR18 Mar 06 1000
MAR25 Mar 06 1300
MAR01 Apr 06 1450

I need to sum the sales for say all of march up to 25-March quot;C9:C12quot;
using a Month marler cell and a date cell, so I could enter Feb in one
cell and 18-Feb in another and it would um that range. Any ideas?Sorry all, I can use
=SUMPRODUCT((A33:A58=G34)*(B33:B58lt;=G33)*(D3358) )

G34 is Month marker, B is week ending date and D contains data.