Guido wrote:
Putting on weight is bascially as simple as "calories in vs. calories out". Burn off more than you consume and you won't gain weight. Eat more than you burn off and you will.
Go to
www.fitday.com and you can start a profile and start tracking what you eat. You can establish your BMR (basal metabolic rate - which is the calories you burn on a daily basis through your normal activities).
From there, if you are looking to put on quality weight, start lifting heavy. That means compound movements using free weights such as squats, bench, deadlift, pullups, and overhead lifts.
Consume 500 calories per day over your maintenance calories. Try to consume 1gram per pound of bodyweight of protein. You should gain 1 lb of quality mass per week. If not, then bump up the calories even more. Keep doing that for a few months and you'll notice some profound changes.
I managed to go from 140 lbs (which I had been stuck at for about 9 years) to over 190 lbs in about 7 or 8 months and I was a LOT stronger. I'm now at about 210 lbs and much stronger and just as lean (bodyfat percentage-wise) as I was when I weighed 140.
Best advice so far! Do not forget cleans/rows as well, and dips are also nice. If you are really serious about getting some muscle you should invest in some form or resistance exercise equipment or join a gym. Most of the equipment you'd need for a simple yet effective weightlifting program can be picked up for pretty cheap.
If you do decide to join a gym/buy some weights/resistance equipment a simple way routine to start with would be something like this
Squats
Bench press
Deadlift
and
Squats
Military press or some other overhead exercise
Rows or cleans
If you're starting out you'll probably want to do 3 sets of 5 reps or 5 sets of 5 reps for every exercise except for the deadlift which should be 1 set of 5 reps. You should switch off between each workout after taking a rest day in between (do the top workout, take a rest day, then do the bottom workout, take a rest day, then do the top workout again and repeat). Its a fairly easy program, as its only 3 exercises per day, 3 days of the week. After a few weeks of that you may want to start working in dips and pullups/chinups, as those exercises really build up your upper body.