Well, first of all, you need to find Barioth in the game world. This can be a bit challenging as it's a powerful monster. Once you've successfully hunted it down, you'll get various parts like its fur, claws, etc. These parts are essential for making the Barioth Armor. You then go to the smithy or the armor - making place in the game. There, you'll see the option to craft the Barioth Armor if you have enough of the required materials and some in - game currency.
You can usually obtain Barioth Armor in Monster Hunter Stories by hunting Barioth and collecting its materials. Then, take those materials to the appropriate in - game vendor or crafter to have the armor made.
In Monster Hunter Stories, to get the Barioth Armor, you have to engage in battles with Barioth. Barioth is a formidable foe. When you defeat it, it drops specific items. These items are what you use to create the armor. The game has a system where you gather resources from monsters you hunt. For the Barioth Armor, you'll need to keep hunting Barioth until you've amassed all the necessary materials. After that, it's just a matter of finding the right NPC (non - playable character) in the game who can craft the armor for you. Usually, it's the local armorer. They'll take your materials and some money and create the beautiful and powerful Barioth Armor for you.