Hi Determined One,
You should visit the
www.sgrho1922.org message board, particularly the prospective section.
I would say express your interest, get to know the members, and continue being involved with the chapter activities and community service.
Keep in mind that Sigma Rushes are by invitation. Should you be fortunate to receive an invitation, it is at that time where you will receive necessary information for membership.
good luck on your pursuit!