IMHO the best place to start is YouTube. Hubitat has a series of very brief how to videos that are very helpful. After that do a YouTube search on "Hubitat" and you'll find plenty of good videos.
If you are transitioning from another system take the time to learn the correct way to unpair/disassociate your devices from it before shutting it down, and factory reset all the devices. With that done try adding a few devices. If I were starting over I would start with my ZigBee devices since they were the easiest. Then move on to Z-Wave devices.
As you work through those initial steps and have questions or run into issues hop on the forums here and post your questions. There are plenty of people willing to help.