Sebastian's Roller Skates by Joan de Deu Prats, illustrated by Francesc Rovira

From chapters.ca:
Sebastian didn't talk very much, even though he had a lot to say. He wanted to tell the barber not to make his head look like a billiard ball. He wanted to tell the neighbours that he hadn't grown all that much. And, he wanted to ask Esther, the little girl who sat in front of him at school, if she wanted to be friends. But he couldn't. He couldn't say any of those things. Sebastian was shy. He was very shy. And then one day he finds an old pair of roller skates in the park. Roller skating is hard to learn, but if you practise, and practise, and practise, and then if you forget about worrying, and forget about falling and just skate, well, everything changes. And sometimes if you forget about worrying and forget about blushing and just talk, well everything changes again.

Originally in Spanish.