How do different Indifference Curves relate to each other?
Each indifference Curve represents a different set of indifferences for different bundles of goods. Assuming the three Indifference curves are labeled I1, I2, I3, with I1 being the bottom one and I3 being the top one. 

Take a bundle on I1. The consumer's preference is indifferent to any other bundle that is on I1, but would prefer every other bundle on I2 and I3 to the bundles on I1.