HI Saffaa

If you are not doing some training then you won't gain any worthwhile weight - you can eat double what you are, and the only thing that will happen is that you'll get fat, which is probably not what you are talking about when you say you want to gain weight. You need the training stimulus to be there so that the muscles will grow. The right diet helps, but most people in the western world aren't short of protein in the diet anyway (except vegetarians in some cases), and so weight gain should not really be a problem if the training is being done.

Now, with regards to training, you need to be doing resistance exercises using weights. If your aim were to build muscle, the following guidelines will help you:
• Perform 6-10 reps at a high intensity - use a weight that you could lift 12 to 15 times
• Perform 3-4 sets
• Rest 30-60 seconds between reps
• Train each muscle group at least once or twice a week
• Allow 48 hours rest between each muscle’s workout

If your aim were to tone muscle, the following guidelines will help you:
• Perform 10-15 reps but at a much lower intensity - use a weight that would allow you to lift the weight at least 25 times.
• Perform 4-6 sets
• Rest 30-60 seconds between reps
• Train each muscle group at least once or twice a week
• Allow 48 hours rest between each muscle’s workout

A really good website that you can go to to find out more about weight training is the following:
http://www.health24.co.za/specials/buc/buc.start.asp
It contains good advice, explanations and assistance with the different types of exercises for different body parts, and even programmes for different types of people. Well worth a look

Regards