I think the answers you are looking for are in the thread you referenced:http://boards.ancestry.com/topics.dnaresearch.generalresearc...
but I'll give a quick summary.
You took the autosomal test. What it is doing is comparing your DNA against others who have tested, and if there is a match, compares your family trees to try and determine where that match might be.
Haplogroups are typically determined by the Y chromosome test which is totally different. However, the test you took does look at some markers on the Y chromosome that might identify your haplogroup, and then maybe not. To find that you need to run 3rd party tools like Promethease.