Hi. Welcome to RR.
In the blue bar above click on databases. Click on your state, then county, and look for the agency you wish to monitor.
Digital is indicated if you see P25, Project 25, APCO 25, or if a trunked system, a "D" in the mode column.
There is also a forum for your particular state where members familiar with your area could also give you some localized assistance.
If price is not an issue, I recommend that you purchase a digital scanner as this seems to be the trend.
Good Luck.