Conversion of textbox value into DATETIME

Hi, I'm new to c#. I have a textbox where the user types in a date- The program must select rows from a database where the date entered in the textbox matches the date in the table. But textbox value is in text type and the value in table is in datetime type. So, please do tell me how I can convert the value entered into the textbox into datetime form. Advice would be most appreciated. Dhivya