color header form when i minimize it as in excel

First of all, you can use the MinimumSizeChanged event of your form so that you can code something. And I guess you will also have to handle the MaximumSizeChanged event. So in Visual Studio, in the designer, when you select your form these events are listed in the properties window. Else you can still have access to the event like this :
this.MinimumSizeChanged += new System.EventHandler(this.Form1_MinimumSizeChanged);.
But after that, actually I didn't understand to which color you refer in Excel.

i don't want change color header form ,when i do minimize form
form.bmp

Thanx