The one I had in mine is just the one it was pierced with.
Around here you can get the hoops from Walmart. They are just the horseshoe looking ones. Just make sure it the the same gauge size.
You could try getting some from Ebay. I have got a lot of body jewelry from there. I just make sure it’s new in the package and I clean them when I get them.
I just kinda pushed mine through. It helps a lot if you fold them, put them through, and just let go.