I am in my early 40’s and my training revolves around improving strength and conditioning, maintaining muscle mass and mobility, and trying to reduce body fat, so my training may not match your goals.
If your goals are more athletically or general health oriented then Joe Defranco’s Westside for Skinny Bastards 3, Jim Wendler’s 5/3/1, or any of Chad Waterbury’s stuff would be fine.
If you are more interested in bodybuilding, I would look at Kingbeef’s old thread it was something like “do this routine instead of that dumb one,” I believe. He posted a lot of bodybuilding routines in it. I’ve heard the Mountain Dog articles are good too, but I have no experience with them.
@T3hPwnisher gave you general dietary guidelines. I guess I would add that if you stick to eating a lot of lean sources of protein it would probably difficult to gain a lot of fat.