Can you help my doggain weight.. it's a pointer... though he eats a lot.. three meals a day.. mainly vegitarian.. but still le looks so lean.. evan stray dogs look better than him in size... though he is very active.. but I don't know where does all the food he eats go.. help me.. he is about 11 months old?

Dog are carnivores... they need meat in their diet to thrive.
Take your dog to the vet and get him checked out, if he has not been given proper nutrition his bones and joints may not have developed properly, if he is not in good health he may be loaded with parasites.

Have you had a discussion with your vet? What does "three meals a day..mainly vegitarian" mean? What are you feeding him and how much food does he get per day? Young active dogs have a tendency to be on the lean side and that is much healthier than an overweight dog. Does he look like he is starving, are his pelvic bones or is his rib cage protruding? Labman uses a web site from Purina where you can evaluate your dog's weight. Please click on this link and see where your dog fits in:
LongLiveYourDog.com - Life Span Study - Rate Your Dog
If he falls into the "too thin" category, you need to make an appointment with your vet for an overall evaluation, health check, and discussion. If everything checks out okay and he is healthy, you simply might need to up his caloric intake, possibly switching him to a working dog chow. But, your veterinarian is the person you need to rely on to help you with this issue.