Up in the top right, under the
help v drop-down, there are two important links:
The first goes to the tour, and the second goes to the help center. Both contain a lot of valuable information about the current site, in different formats (one as a walk-through, and one as a series of FAQs).
If you've been through there and have a specific question you don't feel is answered there, follow the third link, which brings you here. You can search for previously asked questions that might provide an answer, and if that still proves unhelpful, ask your specific question.