To mine Netherite in Minecraft, you need to go to the Nether and mine Ancient Debris, which can only be found in the Nether. According to IGN, the best level to find Netherite is between Y=8 and Y=22, with most Ancient Debris spawning at Y level 15. Therefore, it is recommended to mine at Y level 15 for the highest chance of finding Ancient Debris. However, it is important to be cautious of lava lakes that may be below you while mining.

It is also worth noting that Ancient Debris needs to be smelted in a furnace or blast furnace to turn it into Netherite Scraps, which can then be combined with Gold Ingots to create Netherite Ingots.