I'm bit new to C#. I just want to change the start up form in my project. (This is a windows form application). There is a field named with STARTUP OBJECT and a dropdownlist in Project properties. But my problem is I have created few forms in my project and those forms are not loaded to above mention dropdown list. (It is loaded 2 items which are "not set" and "MyProject.program") Due to that, I couldn't be able to change a startup form. Please show me a direction.

You will have a file called Program.cs. This is the execution entry point of your application - or more specifically, the static method called Main in this file is. In this method, one of the last lines of the Main method reads something like:

Application.Run(Form1);

Change Form1 (or whatever form it actually reads in your file) to be the type of form you want displayed as the first view of your application.