How did the first people to arrive in the Americans support them selves
I’m assuming you mean the first successful colonists (meaning not Roanoke), who were hunter-gatherers, but soon switched to an agriculture-based way of survival.
For example, Virginia, the first colony, after the Starving Time during the winter of 1609-1610, realised that their location was prime for agriculture (they settled right on a river, providing them with super fertile soil). As such, John Rolfe planted some tobacco and Virginia later went on to be one of the richest, most successful colonies in America.
For more specifically, you have to explain who were those first people that you mention about ? Are they Native American or colonists ?