We've featured various content concerning how to take care of and cook with a cast iron pan before, but the video below from Tasty should tell you all you need to know.
Cooking with cast iron is a real joy and a good cast iron pan, if you take care of it well, should last a lifetime. But, it takes some effort to keep it in tip top condition, from seasoning it correctly with the right kind of oil to cleaning with kosher salt, and always, always ensuring it's bone dry to prevent rust. You also have to beware of too drastic a change in temperature too when cleaning, to avoid cracking.
Take a look at the video below if you're thinking of investing in a cast iron pan or have one already and want to check you're looking after it correctly. Also, check out this infographic detailing how to care for cast iron pans.