I'm a skinny guy, gain weight but lose it quickly. is this a condition of not any tips how to gain weight quick ?

Most likely that: You are an ectomorph. As some people just have trouble gaining weight and maintaining it. While it is still reasonable to review this with your doctor to make sure there isn't some sort of concerning hormonal/metabolic issue complicating this picture, but it's more likely just your baseline metabolism. Gaining weight will require a tight balance between exercise and how much you are eating.