How to control data field

In my application by clicking on date field pop-up calender will appears. In that pop-up calender we have to select date,month and year. I am trying to give data through excel sheet, but it is not taking those values.
I need java test script to control date, month and year fields.

I am giving static value for the date field in the following code.
but i want to give dynamic values through excel sheet.

selenium.clickAt("id=f_date_a",from_date); //from date
selenium.click("link=18");
selenium.clickAt("id=f_date_b",to_date); // to date
selenium.click("link=19");

can any one help me..