Total N00b Trigger Question

How do I change what units and resources are given when I create the triggers "Create Starting Units" and "Set Starting Resources"?

I want a single unit of my choice to be created at start locations. No buildings, just my unit. How do I do that? And I want the unit to be different for Orcs and Humans.

The units I want to be created are custom units, not under the standard units category.

Also how do I make it so there's no unit inside the start location? Like there's usually the town hall, how do I make it so it's not there? :( thanks so much

Just remove "create starting units" , "starting resources" and then do "create unit" and just choose what type of unit u want :D