Farmer's Market Bag

I’m just starting the Farmer’s Market Bag in Weekend Knitting. When making the base, do I use all of the double pointed needles…or just 2? I’m casting on 13 sts and making 59 rows. After I cast these off I will then pick up sts on each side of the piece I make…but back to the question of all of the double pointed needles or just 2.

You’ll just use two needles for knitting back and forth.