Girls find too skinny guys even less attractive than too fat guys. I guess that has to do with the dominance big men express.
So as a skinny guy, you want to become a little more muscular and muscled. I myself was always the smallest and skinniest guy is class. The boys with an average height and body could fold their hand around the thickest place of my arm. So yeah, that's pretty skinny. I started working out a couple of years ago. I started, quit, started, quit etc. I never got anywhere.
I started working out full body 2-3 times a week three months back. I combined it with eating healthy and regularly, and bought weight gainer and whey. The first gives you an extra layer of fat to burn, so you won't burn your muscle. The latter is the basic material muscles are built from. You need this as skinny people burn fat very quickly so you won't have enough. Whey is needed to build muscle.
Yesterday someone told me that i was really muscled (in front of a girl, whose eyes began to shine at me ) and that he wanted to have my body. A great compliment, considering where i came from. Hoping not to sound arrogant, I have to agree with him when I look in the mirror.
My advice to short skinny guys is to do the same: hit the gym. A great body triggers attraction for a short-term sexual relationship. Use the weight gainer and whey. I drink one shake of each of them a day. WG before working out, whey after. Also make sure that you don't work out at home. I have done that, and so does the guy who complimented me, but a gym is 10x more effective. Last year when I did the same (another time I quit) I went on vacation and could just see and feel the women staring at me. As I had fear of approaching women and no game, it didn't turn into anything. I'm hoping to do a LOT better this year.
Don't give up after a couple of times. It's like a barrier you have to go through. The pain will lessen after a couple of work outs and if you keep a disciplined schedule, you should get accustomed to it and not minding to go to the gym anymore. You'll start liking it.
Best of luck out there. Pain is gain.