You have to follow the same pattern you used for the second row to make the next ones:
- chain 3
- make as many dc as the ones below
- add 2 dc at the end of the side
- chain 4
- make 2 dc in the same hole
- continue with the other dc!
Make as many rows as you like, I made 7 and closed.
Your first granny square is ready!
...you have to make other 16 squares now!
They must be 17 in total.