Salena grew up in Eagan, Minnesota, a suburb of St. Paul. She graduated summa cum laude from the University of Minnesota - Twin Cities in 2009 with a degree in Psychology and minors in Political Science and Spanish. She attended the University of St. Thomas School of Law in Minneapolis and graduated in 2012. During law school she was involved in many student organizations and worked at the Jacobson Law Group as a law clerk in the field of tribal law and governance.  After graduation Salena served as the Legislative Assistant to Senator Jim Carlson of the Minnesota State Senate.

In November of 2013 Salena married her husband Jared Koster and moved to Iowa, where he owns the Jackson Millwork Company in Spirit Lake. Salena joined Sackett Law Firm as a Paralegal in July of 2014 and became an Associate after being admitted to the Iowa Bar in September of 2014. Salena is also licensed to practice in Minnesota.

Salena is a Director on the University of St. Thomas School of Law Alumni Advisory Board as well as the Chair of the Alumni Giving Committee. She also serves on the Iowa Child Advocacy Board as a Court Appointed Special Advocate and member of the Foster Care Review Board.