The basic equation is 1) lift heavy stuff and 2) eat more calories than you burn. It really is that simple. If you're already on a strength training program, stick on that program and use progressively heavier weights. If you aren't, than the question isn't how to pack on muscle it is how to lift weights (or what program to use).

For the second step, develop a habit of food intake or count calories. Maintain calories/your habit and track your weight. If you're losing weight you know you need to add calories, if you're maintaining, you know you need to add calories.

I'm kinda close to you - 5'11" 175lbs, 12% bodyfat. I eat the same(ish) amount every day and was maintaining weight. I added 150g of carbs a day to my diet and have been steadily gaining about 1lb a week, and most of it is muscle.

If you get a little more advanced you can look into macronutrient balance, nutrient timing, etc. but if you haven't done anything to bulk before, no need to over complicate things now.

Also, take about 5g of creatine monohydrate a day. Doesn't matter when, just do it.