What is the significance of the sunnah?

Sunnah is the sayings/doings (behaviors/actions) of the Prophet Mohammad (pbuh). They have been memorized, and written down from those who were alive and close to him (his companions) during his lifetime and are used to this day along with the Quran as guidelines on how Muslims should act/speak. So basically Muslims use the Prophets sunnah for example if there is a conflict on how one should pray correctly according to Islam or how one should treat his neighbors, etc. One can then research the Prophet's actions and ways of carrying out such actions as praying and treating his neighbors and act accordingly. It is another source to look at in addition to following what is in the Quran.