Need expertise! "How do I go about putting something on ebay or Craigslist?",?

With my sister-in-law’s passing, she had a beautiful set of 12 piece service of Mikasa dinnerware. Most of it hasn’t been unpacked for 17–20 years. All the serving dishes and trays and everything else that would go to a complete set. I don’t know anything about ebay or Craigslist. I believe the pattern is Cezzano, or something liket that, it is like watercolor floral. Really pretty. How do I go about putting something on ebay or Craigslist?