Heaven:
Fr. Mike Schmitz: How to get to Heaven
Hell:
Fr. Mike Schmitz: Hell is Real
Purgatory:
There are a couple of good videos with some more detailed answers (see below), but the easiest, simplest explanation is
"Purgatory isn't a just a place, it is more of a process, like a car wash. Imagine a man who gets his car cleaned before he takes out a woman for their first date. Just like a car wash is a cleaning process for a car that is going somewhere where it is important for it to be clean, purgatory is a cleaning/purification process for our souls before we enter into Heaven."
“What you should know about Purgatory?” Father Mike Schmitz with Ascension Presents video
“Purgatory: Explained” Ask Joel with Lifeteen
As always, we are working to expand our list of resources. If you have anything to add, please let us know!