Help with the sentence

Hailing from the hills of Brentwood in LA, Mark had come of age in the fifties and sixties, atop a canyon, with miles of wooded nature spread out before him and twinkling light of the city beckoning below. My background was less lofty, but not less intense.

I have no idea what these 2 sentences mean. What does "Mark had come of age....", "atop a canoyon, with miles of wooded...", "my background was less lofty, but not less intense" mean?