I'm developing a web application that provide a service of online reservation, and I need to save the data (for example in a specific day and access to them).
How can I do that.
Is it possible using : System.Web.UI.WebControls.Calendar
You will want to use the Calendar Extender control in the Ajax toolkit.
Sample: http://www.asp.net/ajax/ajaxcontroltoolkit/Samples/Calendar/Calendar.aspx
How to install the AJAX toolkit: http://www.asp.net/ajax/tutorials/get-started-with-the-ajax-control-toolkit-cs
Video on how to setup the calendar extender control: http://www.asp.net/ajax/videos/how-do-i-configure-the-aspnet-ajax-calendar-control
Basically, You have a textbox. When the user clicks on the textbox, they get a nice little javascript popup that allows easy selection of a date. The end result is a string that gets saved in the textbox.
You can convert this to a datetime by: MyDateTime = datetime.parse(MyTextBox.text)