How to create below grade garage/basement with descending driveway from street level?

[Adriancox]

Hello,
I have a design I'd like to work with of two townhomes
that have a garage and basement that is at -5' from street level.
How to set the elevation of that part of the house and show that
the driveway descends downwards?

Also, the total structure is 30' with a 5' roof allowance. I'm not
clear how to measure the entire structure so that I see how far from
street level this is at?

Thanks in advance
Adrian Cox