See Part 1 of Eivor's Crochet Granny Square Tutorial for how to crochet the centre section of the granny square — rows 1 to 7 — which crochet stitches are used to make this square what kind of yarn and hook we used create the square in this tutorial.
See Part 2 — row 8 — for how to edge the centre section and make the loops with picots.
Part 3 — rows 9 to 11 — covers how to finish your Eivor Granny Square.
If you simply want the pattern instead of the tutorial see Eivor's Crochet Granny Square Pattern.
sc into corner, *ch 6, sc into third stitch of loop, ch 8, sc into 8th stitch of loop, ch 6, sc into corner of square, repeat from * 3 more times, ss to finish row
This is what your square should look like now.
*sc 8, sc 10 into next chain space, sc 8 into next chain space,
repeat from * 3 more times, ss to finish row