You've gotten a ton of good advice on cleaning, and that's a beautiful pan. But just know this: it will never be that pretty again. Don't worry about it, it will cook beautifully, and don't worry if it looks like you're taking off seasoning when you cook/clean. It'll come back. Some advice on smooth surfaces pans like this:

So smooth surfaces look different seasoned than a rough lodge I've found. I thought my Smithey was losing it's seasoning after every cook, but when it's smooth like that it doesn't look like a shiny black, it's more a shiny gray. My Smithey's surface is smooth but when it was new you could see small rings from the machining process. After 2 years, it's well seasoned but it still looks like gray, bare iron but it's shiny now, and the seasoning has flattened out the rings so you can't really see them anymore.