Try this:
http://www.denverareapanhellenic.org/
Not sure where you are in Colorado... but at least that gets you started.
Growing up in CO, I don't remember Greek life being "talked up" very much while I was in high school. In fact, the only exposure I had before I got to college, was a small table about sorority recruitment at one of the CSU visit days. (I did not end up going to school there).
You may have to do some digging to find active sorority alums to write you recs. Did you try asking your teachers, members of your church, your mom's friends? You'll be amazed at who comes out of the woodwork.