Over 50 leaders from the colonies met in secret in 1774, in Philadelphia, before the American Revolution began. All 13 colonies were represented except for Georgia. These leaders wanted to organize resistance to the Intolerable Acts.
The Second Continental Congress met in 1775, after the Revolutionary War has begun. Things were not going well. The army was disorganized. The Congress asked George Washington if he would accept the job of getting the Continental army in shape to fight. Washington accepted. The Congress also wrote the Declaration of Independence and the Articles of Confederation.
It took time and thought and compromise to get these jobs done. The final compromise "to form a more perfect union" was the Constitution of the United States, ratified by all 13 states in May, 1790.