The purpose of the Second Continental Congress was to come up with a way to present the complaints of the American colonies to the British. They were first called in to session in May 10, 1775.
The first session was called when the British marched into Boston and tried to arrest patriots for voicing their unhappiness against British rule. Since the battle of Concord and Lexington had just recently taken place, the delegates of the 12 colonies decided to meet in Philadelphia. They drew up a statement of how they felt about the actions of British Parliament.
By 1776, the British crown was not taking any actions to improve upon the complaints that were made by the American colonies. That is when congress decided they would pull away from Great Britain to function on their own. The delegates of the Second Continental Congress went on to draw up the famous Declaration of Independence. Once that was done, they wrote the provisions that would lead to the forming of the American Continental Army that would defend the colonies during their fight against Britain for freedom. Congress then voted to start printing money in an effort to finance the military, and the fight for independence began.