You can add new doctors and staff members to the site by going to the people channel and adding new people.
Once here fill in the fields and add a photo. The photo is should be square and a minimum of 500px * 500px - larger is fine. If a photo is not added then the fallback photo found at Globals will be used.
Once you've created the entries for staff and doctors you can add them to the Our Staff and Meet Our Physician pages by editing those entries.
Add the staff or doctors to the entry and then re-order by dragging/dropping their names up and down.