How to assign value to Dropdownlist ?

Hi Friends ,

 

I need to assign the value to dropdownlist. Which i load the branch name in it. Based on user authorization .,the branch name will differ. I need to assign to dropdownlist and dropdown  selectchange event also need to raise.

 

Because i have handle functionalities with in the dropdown select change event.

 

Provide me suggestion regard this.with the simple code example.

 

Thanking