If you want to participate in Legendary Crafting, you’ll need certain items. These items include a special base item from Blacksmithing, Leatherworking, Tailoring, or Jewelcrafting. You’ll also need some Soul Ash, the Memory of the Runecarver Legendary Recipe, and a pair of different stat scrolls from the Inscription profession.
Once you have all these in hand, take them to the Runecarver in Torghast. Mix them together, and boom, you have your Legendary. In case you missed it, there’s a zombie plague in Shadowlands right now. Additionally, a recent LUA issue was apparently fixed by Blizzard recently as well which seemed to have affected several players.
Finally, you check out Robin’s take on restarting in the Shadowlands beta right here.