SQL - First steps

http://www.w3schools.com/sql/trysql.asp?filename=trysql_select_all

Perform following queries:

1. The list of ContactName of table Customer.

2. The list of ProductName that have 1 as CaterogyID of table Product.

3. In the Product table, instead of the ID (for CategoryID and SupplierID), display the names of categories and suppliers, all that in a single request.

4. Create a user table similar to what we can find in a social network. Think about the fields required and the structure.

5. Which fields will be repeated? Is it possible to generate tables as 1,n. And / Or what am I asking you to do?