The squares are made with a double-ended hook, more info in part 1.
There is a tutorial available in part 1, you need to know the basics of Tunisian crochet.
You can use any yarn you like. When you are a beginner use thicker yarn and a larger hook. The size will depend on your yarn, hooksize, and tension.
You have to determine your hooksize by making a regular Tunisian crochet swatch.
The Cal contains 34 squares in 4 sizes 10/15/20/25 rounds.

Release Dates
Part 1 – available - 2 squares
Part 2 - available - 3 squares
Part 3 - available - 3 squares
Part 4 - available - 3 squares
Part 5 - available - 2 squares
Part 6 - January 16 - 3 squares
Part 7 - January 23 - 3 squares
Part 8 - January 30 - 2 squares
Part 9 - February 6 - 3 squares
Part 10 - February 13 - 3 squares
Part 11 - February 20 - 3 squares
Part 12- February 27 - 3 squares