Name two tricks Henry could do with his yo-yo.

Here are the answers to your questions based on the provided text:

1. Step 1: Locate the information about Henry and Finn in Smith's shop window. The text states: "He tugged Finn to look at the street in Smith's shop window. 'Ali Alabama, World Yo-Yo Champion, is coming to the Town Hall this Sunday!'" Henry and Finn saw an advertisement or poster about Ali Alabama, the World Yo-Yo Champion, coming to the Town Hall.

2. Step 1: Find the part of the text that mentions Henry's age when he received his first yo-yo. The text says: "Grandad had given Henry his first yo-yo for his ninth birthday." Henry was $\boxed{9 \text{ years old}}$ when he got his first yo-yo.

3. Step 1: Identify the tricks Henry could perform with his yo-yo. The text mentions: "He could spin the yo-yo across the floor in a trick called Walking the Dog." and "He could even do Around the World, spinning the yo-yo through the air in a full circle and flicking it back to his hand." Two tricks Henry could do were $\boxed{\text{Walking the Dog and Around the World}}$.

4. Step 1: Search for the name of the World Yo-yo Champion. The text states: "'Ali Alabama, World Yo-Yo Champion, is coming to the Town Hall this Sunday!'" The name of the World Yo-yo Champion was $\boxed{\text{Ali Alabama}}$.

5. Step 1: Find why Henry thought Ali used special yo-yos. The text says: "'How come his string never gets twisted? He must use special yo-yos,' Henry whispered to Grandad." Henry thought Ali used special yo-yos because $\boxed{\text{his yo-yo string never got twisted}}$.