COUNTIF Using two Criteria

Hi

I've had a search around the site without much luck.
I'm trying to count up a number of "won" estimates during a certain date period.
I have attached a simplified example of my data sheet.
Each row shows an amount of data entered for each contract, including the date and whether it was won or lost.
I want to count up the number of won estimates by cross referencing against the date so i can see how many were won during a certain month.

Cheers
Mark