The city of Shawnee is in Pottawatomie County, Ok. You need to know the country, state, county and municipality or agency name to look it up in the RadioReference.com database (The Database tab on the
RadioReference.com web site). This is what I'm referring to when I say "RR database".
If you want to see what it looks like, go to the Database and drill down by country and state to Oklahoma then look for statewide trunking systems. If you don't find what you're looking for, look under the county for the same info both in conventional and trunked systems.
As a scanner newbie there's no way you'll be able to program the trunked system in by hand (probably) so I suggest you invest in a programming cable and appropriate software plus a premium membership to radioreference.com which will let you load up the scanner for you.
The State of Oklahoma Trunking System (Motorola Type II SmartZone running Analog and APCO-25 Common Air Interface digital) does indeed have the talkgroups you want. You'll need to enter the site's control channels into the scanner and the desired talkgroup ID with their text-tags. Like I said - easier with software and a paid subscription.
Even if the data is correctly programmed into your scanner, if the talkgroups you want to listen to are using digital, you'll need a much better signal than for analog reception. I often hear digital comms as nothing but a series of clicks and pops or buzz-saw sounds unless I'm stationary and/or right next to one of the repeaters.
Looking at the PRO-107 it appears this is an analog trunking scanner and will not decode digital (APCO-P25) signals anyway. If you want to listen to any digital talkgroups, you'll need a different scanner. Fortunately the Pottawatomie County police and fire are all using analog voice.
You may want to check into updating the built-in frequencies with the included PC interface. Without reading the manuals, I can't tell you if or how that would be done but it sounds like it's an option.