Yulia informed you that the quickest way to reach the Lance is through a portal to Farwood that lies within the Temple of Heorot. Before you can enter the temple, however, you must raise the bridge to it using a relic known as the Blessed Horn.
After some complications involving a fortress of Wengari, you retrieved the Blessed Horn from the nomadic tribe that guarded it and entered the Temple of Heorot. After exploring the temple, you found a large room with a dais on one end, defeated its guardian, and took the portal to Farwood.