Step 1 is definitely recording one of your games - this is a great free tool I've found for simple recording:
OBS (Open Broadcaster Software): https://obsproject.com/
Apply a couple hotkeys for start record / pause record / stop record, set a file destination, and you're good to go. The only other thing you might change is the encoder setting - Max Bitrate - and make it low value (e.g. 1000, that'll get you 480p) so that your computer doesn't forever to upload to youtube, should that be a problem. If you love uploading in HD, set it to 3000.
Arcane Tracker ( https://play.google.com/store/apps/details?id=net.mbonnin.arcanetracker ) is not related to HearthArena at all, but it works as an overlay on Android for deck tracking and will auto-detect decks.
I use OBS (https://obsproject.com/) for video recording. No idea if it's still the best tool.
There are other HS-specific tools for non-video tracking (e.g. http://hearthstonetracker.com/) that are faster to review post-game.