Become an avid lifter instead. Plus, what Max said.
Really, that's a super-super-super vague "question" you're asking. There are tons of articles with nutrition plans and workouts to build size, but there are a few factors involved.
Your age is one. Not necessarily a negative, but it's always tricky putting on size when you're older because there's not as much leeway for fat gain. Your current size is another factor. Height, current weight, and current fat level will influence how much/how fast you could/should gain.
And then the training. If you're still running a bunch, that's gotta be reduced (not necessarily eliminated) if gaining size is the priority. A well-designed weight training plan is essential. A lot of guys in the Over-35 lifter's forum seem to like 5/3/1 but any good plan can do the job.