When trying to get people you don't know to email you back there are a few things to do.
1 - Contact them through email, not social media. Pros use email.
2 - Keep it short and to the point. You did that.
3 - include a URL of some kind and maybe samples of your work. Everyone has some sort of public online presence. If you don't have one it makes you seem amateurish and like you're not serious. You have to show what you're doing. People get hired because they're already doing the job they're trying to get hired for. No one's going to sense you have something special in you and then just open the door of opportunity for you unless you're dad owns the company.
4 - Don't tell people you want to take their job. It's threatening, not flattering. I don't want people competing with me for my job. Because you were in the marines I'm giving you real advice but otherwise I wouldn't be e-mailing you back.
5 - Learn to gather information on your own before emailing a stranger. Most art directors and editors are not going to respond to your emails. Make your first impression count. Be clear about why you're emailing.
So my overall critique of your meal so far is that we talked on social media and now you've emailed me and I personally don't know if you have worthwhile skills or not. You should have sent art samples or samples of what you do without being asked. Most art directors just skip to the samples and then read the email text later if they're interesting.