Harry rolled over in bed, a series of dazzling new pictures forming in his mind's eye….He had hoodwinked the impartial judge into believing he was seventeen.…he had become Hogwarts champion…he was standing on the grounds, his arms raised in triumph in front of the whole school, all of whom were applauding and screaming…he had just won the Triwizard Tournament. Cho's face stood out particularly clearly in the blurred crowd, her face glowing with admiration….
Harry grinned into his pillow, exceptionally glad that Ron couldn't see what he could.
There are few things I don't get from that sentence:
What does "grinned into his pillow" mean? Is it his face burying into his pillow while grinning or something?
Why did Harry feel exceptionally glad that Ron couldn't see what he could? Is it because Harry felt shy about it?
Can anyone help me to understand it?