Key Value Pair... in C# Combo Box

HI
I AM A BEGINEER TO C# LANGUAGE.

How can I add items to a combobox in value key format?

I was able to add the value only using
ddCombo.Items.Add("HelloWorld");


Can anyone help me?

Thank You
Edit/Delete Message

Look up ListItem. It has a key and value.

ddCombo.Items.Add(new ListItem("HelloWorld", 1));