For setting the values in the Combo Box the following
steps are to be followed :
  
1> Open the Property window of the Combo Box.
  
2> Click on "Combo Values" button to open another window
having a title "List Values".
  
3> Enter a value in the provided Text Box and Click on "OK"
button.The values get added to the combo box,which can be seen
in the combo box which is provided at the bottom of the
window.
  
4> Values entered into the Combo box can also be modified by 
selecting an already inserted value from the Drop down box
and modifying it to a new value and then pressing the button
"Modify".
  
5> Value inserted can be deleted by selecting the value which
is to be deleted from the drop down box and clicking on "Delete"
button.
  
6> After adding all the values and modifying the required values,
clicking on "Submit" button saves the changes done.
  
7> Click on "OK" button of the property window to return back to
the OCM user interface.