Welcome to the RR forums. Here are some excerpts from the easier to read manuals we often refer members to for FAQs:
Uniden Sentinel is available for free for your programming & firmware updating needs. Its easier to read manual is linked
here. Only drawback to Sentinel, particularly with trunked radio systems as far as favorites list building goes is that it imports every site and talkgroup on a given system and then you have to go through the favorites list and remove what you don't want. I strongly recommend
Proscan over Sentinel for favorites list building as Proscan allows you to pick and choose only the site(s) and talkgroup(s) you're interested in hearing without the need to remove everything else you don't need. You get a 30 day free trial you can use to create your favorites lists and after the 30 days elapses, $50.00 gets you two activations. Only prerequisite is a RR premium subscription which you have already.
Your county operates on the trunked radio linked below. Talkgroups designated as modes "A" and "D" on said system can be monitored. Mode "DE" talkgroups are fully encrypted and cannot be monitored. "De", lowercase "e" are partially encrypted meaning some communications can be monitored but not others.
Anne Arundel County (P16) Trunking System Profile
www.radioreference.com
If these terms seem foreign to you I'd suggest having a read at the trunking basics wiki linked below to get you up to speed on the terminology. As previously mentioned, specific info goes a long way here when asking a question but I hope the aforementioned info will help get you on the right path
wiki.radioreference.com