Step 18: Cables
You need to cut the cable housing for your brakes and shifters.
The key thing here is to make sure you have enough housing so it won't bind and keep your bar from turning all the way. Also make sure it does not interfere with the brakes, thats no good.
See how I have the bars turned as far as they will go and I'm holding the housing against the cable stop? Thats the way to do it.