New rider?, don't worry about crank length.

1. Avoid all contact with cars.
2. Keep the rubber side down.
3. Enjoy the days on the bike.
4. If your butt hurts during the first month (or 2), no saddle will fix it completely.
5. Learn to shift at the right time
6. Practice riding a straight line on the road, even when you reach for a bottle or turn your head.
7. Relax your shoulders, arms and hands - Now really relax shoulders, arms, and hands.
8. Get out of the saddle regularly.
9. Breathe more deeply.

Lots to learn before crank length.
Sorry, but i can't see the pics, so i know my answer is incomplete.

For roadies and people riding longer distances or faster speeds, clipless pedals and shoes make it sooo much easier.