Social Media programs and 7th graders-oh no!!!!

This doesn't really have to do with Week 2's homework, but I found this rather interesting.  One night a week I teach middle school students and tonight was the first class for this year.  So I introduce myself to my 25 students as "Ms. Cindy" and give them some background about myself and we talked about a few things before actually getting into the lesson I was to cover.  I mentioned I will be visiting Vietnam in October for part business/part vacation.  They wanted to know if I had Instagram, Facebook, Twitter and a couple of other social media programs I had not heard of.  They wanted to be able to "follow" me and see photos I take and read about what I was doing/seeing in Vietnam.  Instagram was the most popular one mentioned.  So I may have to set up an Instagram account (if I can figure out how and learn how one uses it).  Or maybe a separate Facebook account for my students to access.  I don't know what would be best, as I would like to keep it limited to my students and possibly use it each year as a way to reach them-both past and present students (every year I get a new class of 7th graders).  So I am willing to take any suggestions.  I figure it would be a good way to post stuff between classes, remind them to bring their textbooks to the next class and about any homework due, maybe post little sayings and such, etc.