chart filter from 2 dates

Hi Experts,

I am using WebI 3.1 thin client.

I want my chart to be effected from 2 fiters

1 filter is start date

2 filter is end date

I want my data should be calculated between these 2 dates nad will come in chart.

And I want these 2 filters not as a prompt....I want them at report screen...from there I should be able to select the dates.

and in that case is it neccessary that data type of date column in DB must be date or it can be varchar.

please assist

Its urgent for me.

Thanks & Regards

Nikita