Rounds 2-5

For the next four rounds:

Round 2: inc x 7 (14)
Round 3:
[sc, inc] x 7
Round 4: 21 sc blo (21)
Round 5: 21 sc (21)

Surprise! New abbreviation alert! Meet blo, which means "back loop only."

For round 4, that means you need to crochet 21 single crochet stitches through the back loops of the previous round. 

To find the back loop, first make sure the right side of your work is facing out.

Then put your hook under the back loop of the next unworked stitch. The back loop is the half of the horizontal V that's further away from you:

hook through back loop only

Crochet a single crochet stitch like you normally would, and repeat all the way around the round. You'll know you've done it correctly because you'll have a ridge on the outside of your piece:

round crocheted through back loops only

Also we're color changing in the next round, so pause before you finish the last sc of round 5 and go to the next step.