I am attempting to write some stateful code in Haskell. To this end, I follow this material. At this point, I got my way to monads and functors, and, roughly put, I am confused and can’t make progress with the material. I have this M(Non)WE:

import Control.Monad

data State s a = State (s -> (a,s))

runState (State f) s = f s

put :: s -> State s ()
put state = State (oldState -> ((), state))

get :: State s s
get = State (state -> (state,state))

modify :: (s -> s) -> State s ()
modify f = State (state -> ((), f state))

-- The following 3 rows fail:
instance Functor State where
  fmap f (State s) = State (f x)
  
-- The following 3 rows fail:
instance Applicative State where
  pure = return
  (<*>) = ap

instance Monad (State s) where
  return x = State (s -> (x,s))
  
  op >>= f = State h
    where h state0 = let (val,state1) = runState op state0
                         op2 = f val
                     in runState op2 state1
                     
add :: Int -> State Int ()
add i = do old <- get
           put (old+i)
           
main = do
  print(runState (add 1 >> add 3 >> add 5 >> add 6) 0)

The error message is:

question1.hs:16:18: error:
    * Expecting one more argument to `State'
      Expected kind `* -> *', but `State' has kind `* -> * -> *'
    * In the first argument of `Functor', namely `State'
      In the instance declaration for `Functor State'
   |
16 | instance Functor State where
   |                  ^^^^^

question1.hs:19:22: error:
    * Expecting one more argument to `State'
      Expected kind `* -> *', but `State' has kind `* -> * -> *'
    * In the first argument of `Applicative', namely `State'
      In the instance declaration for `Applicative State'
   |
19 | instance Applicative State where
                          ^^^^^

What am I missing here?

PS. (I am a beginner Haskell programmer. Please bear with me.)