Hi Lex,
You can add a dropdown object to the screen by dragging it from the Add Objects tab in the Toolbox onto the screen. Once it’s on your screen, you can add values to it by selecting Edit. Keep in mind that this is just an object on the screen and not a field in your table. The value set in this dropdown will not be saved when you save the lead.
If you’re trying to add a custom field that can be saved with the lead record, you need to add a dropdown field to your Customer table. Once you’ve done this, you’ll be able to add the field to the screen by dragging it from the Add Fields tab in the Toolbox onto the screen.
I hope this helps.
Audisho