In this quest you have to find Alduin’s Wall to find information about how to vring down Alduin.
First you have to bring Esbern to Riverwood to meet Delphine in the local mead hall. You can fast travel there without loosing Esbern. Delphine will take Esbern to Karthspire. In front of it and inside you will run into some Foresworn who are easy to take down.
The first puzzle is to lower the bridge. all you have to do is make all pillars display the dragonborn symbol which looks like:
Alter there is a field of pressure plates. If you step on the wrong pressure plate you get blasted with fire. The plates with the symbol of the dragonborn (as in the image above) are safe to step on, the others will trigger the trap.
The rest of the quest is straight forward, you have to follow the tunnel to Alduin’s Wall and listen to Esbern talk.