At the beginning stage, just about any workout program is going to show results. You can decide later whether you want to focus more on building endurance, muscle or strength.

General rule for building muscle, 1g of protein per lb of bodyweight. If you find it difficult to achieve that with regular food, then go ahead with whey protein. Chicken breast should be your best friend. Other than that there's eggs, tuna, milk or even vegan sources such as nuts, beans, soy, etc. Key to weight gain is more calories gained than calories burned.