Like all craftable items in Fallout 76, you'll need the Power Armor Station's crafting blueprint before you can make it.
There are several Power Armor Stations scattered all around the world for you to use, but if you want true convenience, you're going to want your own. If you want true freedom in modifying and enhancing your Power Armor's plating and capabilities, you're going to need a Power Armor Station. Sure, you can take a chance and try finding better armor plating out in the world, but that's a well that'll run dry before too long.
Once you've reached a high enough level to wear a fully-equipped suit of Power Armor, you're likely to wonder what you can do to further enhance its abilities.