Hi Pegah,
You know here is United States. Unlike most of the places in the world (and I hope you know where I mean) here you can acheive even the impossible as long as you are the best. With a good and acceptable job experience which is almost a must in US job market you can get your foot in the door and the rest depends on you. The better you work and show yourself the better would be your opportunities for career building and promotion. I applied for some 20 jobs in sicence field and finally got a good one even though I dont have a job experience.
careerbuilder.com, aerotek.com, jobing.com, and monster.com are the best places to look for job.
Good luck with your life in US, I know you will like it here in fashion industry.