If I answer you in French, I hear the interpreter speaking English, which makes things somewhat more complicated. I will answer you anyway, and just try to ignore the interpretation.
In my case, as was the case for my predecessors, the Chair of the Board is selected from among the members. I see this as a wise decision, because the Chair is familiar with the work of the Board and the organization he will be required to lead. In my case, I received a phone call and was asked if my name could be placed on a list of potential candidates. Subsequently, I learned that my name had been selected. That is how it worked in my case.