I cannot understand how to properly fry seafood I don't understand how to properly fry something.
I tried the basics: Use a shallow pan (ceramic), place it on the stove (induction), add oil (sunflower), wait until it gets hot and add something (thawed seafood in my case).
In the advertisements the chefs just swirl the mussels, shrimps, and octopus pieces around and produce some tasty browned pieces. In my case the seafood leaked a lot of water and the oil disappeared somehow. Since the pieces were stuck on the pan I needed to stir with a scraper. All I got were some barely made pieces with a thick brown layer sticking on the pan.

What did I do wrong and how can I improve?
Update
Your suggestions worked.
Yesterday I made about half a kilo of seafood. I dried the seafood, used a bit more oil and prepared it in batches in a non-stick pan.
Thank you all!
Given your picture, I think the correct term here is saute; that is, to quickly fry in a little bit of hot fat. Pan frying uses more fat, and a lower temperature, to create a deeper crust. Probably an overkill for mussels.
For a saute, you want relatively dry (pat dry with towel if necessary - frozen seafood can release a lot of water) ingredients, relatively high heat, and a solid pan that is not over-crowded.  Heat the pan, add the fat, then the ingredients.  Then generally keep the ingredients moving during the cooking. Here is some further direction that details the process.
See also this for a discussion of the origin and use of term/technique.