Building muscle mass?

You should do weight lifting, but it depends on what type of muscles you want.

If you want big bulky manly muscles then every time you weight lift you have to do a lot of sets with a little bit of reps with higher weight than you would be comfortable with. For example, lets say you are doing bicep curls and you are curling 50 lbs (and its a little heavy for you). You are trying to build muscle mass so you would do 10 curls 5 times. Do this from 4 to 6 days a week, and each week add some more weight.

If you want toned muscles then you would do a little bit of sets with a lot of reps and weight that you are comfortable with. For example if you are doing bicep curls and you are trying to tone your biceps then you have the weight that is comfortable for lifting and you would 20 curls 3 times. Each week add a little more weight, reps, and sets. Do this 4-6 times a week.

After your done working out then eat protein. Protein bars are always helpful, and steak, chicken, pork, anything with meat.