You just need to be patient and keep working with him. This can take a long time. He's only 11 months old so it could be several months before he really gets good with the coordination of using a spoon or even getting the knack of using his pincher fingers. This all takes coordination and using the fine motor skills which can take a long time. Keep practicing with him but don't get impatient. He isn't deliberately trying to annoy you. He wouldn't understand that at this age, probably not until he's 2 years old.
I am watching a 13 month old right now who can't use a spoon yet. He's getting better with the finger food, though. And yes, he throws things on the floor too, including his cup. That's why my dog likes to lay by the high chair! :)
Good starter finger foods are things like cheerios, toast strips (without butter), soft veggies and fruits like canned carrots cut up, peas, pears, peaches. Avocados are a good first food. Bananas cut up, waffles. Once he's 1 year you can add more things like scrambled eggs.
Just keep working with him and helping him. He'll get it with plenty of practice! In the meantime be prepared for him to get messy. That's the joy of having a toddler! :)
How long have you been working with him.