What do the boys learn in wringer school? Who teaches the class? What does the teacher tell the boys is most important part of being a wringer?

In the instructions for being a wringer, instructions are clearly spelled out: pick up five birds after the shoot, and wring the necks of any who are still alive. The instructor, who is referred to as a wringmaster, explains the most important part of the wringer's job is to be fast. Speed is very important in clearing the field.