The First Continental Congress was held in 1774 when the Thirteen Colonies met to discuss what they were going to do about the Intolerable Acts that Britain imposed on them after the Boston Tea Party. They decided to ask King George III to abolish those Acts, and in case he didn't do that, they would hold another meeting. He refused to abolish the Intolerable Acts, which is why the colonists met for the Second Continental Congress.
The Second Continental Congress was held in 1775 and brought about the Declaration of Independence, after which America actually started fighting for its freedom and independence.