I have very slim arms becouse i never did any serious workout or physical work more than couple of weeks. I have slim arms, slim legs but my torso is bit fatter. I look ok but realy i want to have a decent looking arms. Guy on the picture you posted is more muscular than i want to be. Anway if i strain my arms well they look quite good. Basicaly its not so much about being very muscular but desire to have more normal arm. Right now my arms are like this;

(note that this is not my arm but it looks very similar)

As for strenght well my strenght is quite good considering that i dont work out and how skinny my arms are. Its realy easy for me to do pull ups. I heard that skinny people should do more reps and less sets becouse we burn to much energy, they say that in gym we must try to lift as much as we can. Also some say skinny people should eat lots of calories. But i dont know if all this is true.

Well, if you plan to get muscle mass or to say it muscle weight obviously you'll have to eat more ;D and not candy or junk food which automatically goes to fat but quality food like proteins as meat, easy digestible carbs such as potatoes, fruit for fibers and so on. It's like with a car, you can't fuel a dragster race car with regular fuel, you'll have to use better refined fuel so same is with athletes and regular non-active people. If you want to build muscle mass, eat healthy, eat more and exercise…and you'll notice the difference in less than a month. There is a question of genetics of course, one of my friends is skinny and is even using protein shakes but still he can't seems to progress although i blame his unmotivation and lack of discipline.

If you want to progress you always lift the weight that you know it will bring you to failure after few sets. Always take the heavier weight that you can lift a bit harder and it will make your muscles fail after few sets…that's the one and only rule for progress in muscle mass.