when i click inside the combo theres not data

You need to take some action to populate the combo's internal list. If you are just hard-coding specific values, you can use code like this in the combo's init():

WITH This
  .AddItem( 'Apples' )
  .AddItem( 'Oranges' )
  .AddItem( 'Pears' )
ENDWITH

Now, if you want 'Oranges' to be the default value, all you need is this line of code:

Thisform.MyCombo.ListIndex = 2

because 'Oranges' is the 2nd item in the list

HTH