Date of birth and wedding date should not be the same.

i am doing a project in asp.net with csharp,in that design page as follows;

Name textbox1

DOB textbox2(calendar image) when i calendar image in that calendar which date is selected that date is diplayed in the textbox2)

Mobile textbox3

Wedding textbox4(calendar image) when i calendar image in that calendar which date is selected that date is diplayed in the textbox4)

Email textbox5

And one insert button.

when i click the insert button suppose user choose both DOB and Wedding Date be the same that time message displays DOB and Wedding date should not be the same.

Date of birth and wedding date should not be the same.how to validate.

for that validation how to do in asp.net with csharp.

please help me.please give the code.