Hey Kevin,
I can't get into too much detail and break it down to you step by step. Reason being the service you will be using to retrieve that information will be a 3rd party service. Like the example I posted in my original reply. Those services are not always free and/or have licensing factors and this maybe the issue with the original example I posted.
Using our Help Center article 'Call Web Service' you can get some further information. But to put you in the right path in terms of the parameters as per the the Help Center article: 'Add any parameters to the web service call in the order in which they are sent to the web service.' in your case depending on which service you use to retrieve the data if they return back both State and City then you would have two parameters to hold that information to use as Action Results.
Also THIS thread on showing an example of the Web Service being used is great in explaining and it also has steps/screenshots.
Lastly as you stated you are new to customization, I would suggest the first course of action is start by watching our customization webinars, having a strong customization foundation will help you put together different areas of the platform.
Take a look at our customization webinars here: LINK.
-- Mortaza