Step 3. Create a new folder named "MyForms". Find the DevExpressASPxSchedulerForms folder. If this folder is missing, you can create it and copy default templates to your project site using the ASPxScheduler control's Smart Tag, as described in the Dialog Forms article. Find the AppointmentForm.ascx form and the corresponding code-behind file AppointmentForm.ascx.cs (or AppointmentForm.ascx.vb if you use Visual Basic). Copy them to the newly created folder MyForms. Rename the copied files to "UserAppoinmentForm" - i.e. UserAppointmentForm.ascx and UserAppointmentForm.ascx.cs (or UserAppointmentForm.ascx.vb if you use Visual Basic).
Do not forget to rename the class definition for the form in the code-behind file - to the public partial class UserAppointmentForm : SchedulerFormControl
Step 4. Check to see whether or not the Codebehind property value of the "@ Control" directive in the UserAppointmentForm.ascx page is changed to the new name of the code-behind file - Codebehind="UserAppointmentForm.ascx.cs". This should be done automatically, if not, rename it manually.
If your project is a web application, rename a custom template class to avoid errors during compilation. To accomplish this, rename the class AppointmentForm in the UserAppointmentForm.ascx code-behind file and in the designer class file to UserAppointmentForm.
Step 5. Change the ASPxSchedulerOptionsForms.AppointmentFormTemplateUrl property, which you may find under the OptionsForms tag (OptionsForms section in Property Pages) to the value corresponding to a new location of the form's template, i.e. ~/MyForms/UserAppointmentForm.ascx.
Step 6. Add new controls to the form. In our case, it will be an ASPxTextBox control with the ID set to "tbField1" and ASPxMemo control with its ID set to "memField2".
Step 7. Add a new class definition file to App_Code folder. Name it "UserAppointmentFormClass.cs".
Step 8. In this file define a public class UserAppointmentFormTemplateContainer that inherits from the AppointmentFormTemplateContainer class. It will provide data from the custom fields for display on a page. You can adjust the data as required.