You first must create a profile on their website to apply to any positions. A couple weeks after my application, I was called and given the opportunity to interview at their headquarters in Grand Rapids, MI. I was interviewed by two women and was asked questions about my resume, availability, and then behavioral/situational questions.
Just know the basic questions about yourself (strengths, weaknesses, personality, etc.) and know how to use them to answer the stranger questions. Don't be afraid to think on your feet!