what is the difference between von and aus? they both mean ‘from’ and I don’t get the difference...

Read this excerpt from leah missbach day’s foreword to wheels of change. in efforts to restart the lives of those devastated by the crushing waves of the 2004 indian ocean tsunami, my husband, f. k. day, and i founded world bicycle relief (wbr). wbr works to provide access to independence and livelihood through the power of bicycles. during our work in sri lanka in 2005-2006, we put more than 24,000 new bicycles into the hands of those rebuilding their lives. since 2006, we have moved into africa where we currently work in zambia, zimbabwe, and kenya addressing oppressive poverty and the aids pandemic by mobilizing volunteer caregivers, students, and entrepreneurs with bicycles. what is the central idea of the excerpt?