Hello,
I've read your description and I'm very excited about this job opportunity. I am determined to work for FREE during a small trial period. I am confident in my abilities and I think I have decent chances of impressing you with great results during the trial period, and I'm ready to do it for free. Recently I have finished my studies in SEO&SMM and I'm up-to-date with the newest and best practices in the industry. I only have a few months work experience but since I'm ready to do the trial period for free I think it's a great opportunity for you to get an excellent Social Media Manager at a lower rate than that of an experienced one, which may deliver no better results.
Kind Regards,
Daniel