The First amendment guarantees right to free expression and free association, it means that government doesn't have the right to forbid people from what they like, and what they can form clubs and organization, and also can take part in demonstration and rallies.
But in order to really participate, we need to know our right - otherwise we may lose them.The highest law in the U.S constitution which has some amendments known as Bill of Rights. This bill guarantees that government can never deprive people of certain fundamental rights which includes the rights to free speech and freedom of religion.
