With the 396XT, you create systems, which are technically the same as banks, except that there is no set number of channels and no wasted space. You determine the number of channels in the system by what you program into it. If you have, say, 75 frequencies to pogram into a specific system, then that system becomes a 75 channel system. You can add frequencies to it or delete them as necessary as the need arises. With banks, you may only have 75 frequencies to program into a 100 channel bank, and you wind up with 30 unused or wasted channels.
You can also create groups, which are kind of like sub systems, within the main system. If you program your municipal system you can divide it up into groups, For example, Group 1 - Police, Group 2 - Fire, Group 3 - EMS, and etc. This is a great feature because if you want to add a new fire frequency, and you want to keep all of your fire frequencies together, you can just stick it into the fire group and you won't have to reprogram all or part of the system. But, I don't want to get too technical here.
You can do the same with trunk systems. Create the system and then program the various talk groups into groups so that adding and deleting talk groups doesn't require a reprogram of the entire system in order to keep specific TGs together.
It will take some time and patience to learn and understand it, so you will need to take it slowly and one step at a time. And, of course, we're all here to help you and point you in the right direction if you run into problems.
I have a 396T and a 996T, which are similar to the XT models, minus a few features, and they are the best scanners I have ever owned.