Go go Configure>Extended Data. Select Work Order and select your field - also make note of the corresponding Cfield number. You may choose to change the display name in this step as well.
Change display type to Combo and then save.
Go to a Word Order screen in Met/Team and double-click on the field in the Extended Data tab (here they are only listed as C23 numbers so look for the C number you took note of or your new display name.) Click on the little gear icon (highlighted.)
That will take you to the combo data field.
Add your values (right click and add) and save: