Set Default in ComboBox

Question

HI Everyone,I'm new member here. First of all,I would like to introduce myself.

My name is Widy gui. widy is my first name and gui is the surename.

 

So I would like to ask how to set default in ComboBox??

 

I have added item in the ComboBox,but I would like to set a default in the combobox so after I run it,it will appear the first item which I added.

 

Here my code to add item in the ComboBox:

 

cmbbxOperator.Items.Add("+");

cmbbxOperator.Items.Add("-");

cmbbxOperator.Items.Add("X");

cmbbxOperator.Items.Add("/");