I just want to be able to not be scared to walk around at night time by myself and to be able to beat up terry and matthew.
First my arms need serious work.

I used to have stomach muscles.

This part is ok for some reason. Maybe lots of sitting.

The part that needs the most work are my legs. To much sitting.

They should make a workout reality TV show for skinny guys who want to be buff. I would definately try to be on it. Until then I am going to make this my personal skinny guy gets buff reality TV show.
This is my target size, lol.

Good luck on the working out. One thing that is important is that it has to be enjoyable. Yes you do need to push your self when you lift but if you enjoy yourself it will make going to the gym easier. You might want to think about taking self defense classes. There are also books and videos for self defense. I don't know what one is the best there are so many.
Good luck. In addition to Jim's healpfull suggestion it also helps to try and actualy have a good time working out. Having uncomfrotable shoes and 'the best of the Mormon Tabernacle Chior' on your iPod spells doom for the gym bunny.
Go for it. I've been trying to put on weight this last year, I've gone from 140 to 170 lbs in the last 6 months. The most important thing for me was to eat more. I could never put on weight no matter how often I worked out until I doubled the amount that I ate every day. You also have to eat consistently. It'll throw your body off missing meals.
Good luck :)