User Controls

You can add the same user control u create thru code also. Suppose u created MyUserControl then use the following code in ur form constructor.
MyUserControl userCtrl=new MyUserControl();
userCtrl.Dock=DockStyle.Fill;  //docking to the parent control
this.controls.add(userCtrl);
 
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toolbox show your usercontrol after successful build of your project
Thank You