If you like, you can mark a specific answer as helpful by clicking on the link "mark as helpful", placed bellow the answer:

Now the answer marked as helpful will appear first in the list with answers bellow the question and the icon with an exclamation mark will be in green:

By clicking on "NOT helpful" the answer will be unmarked as helpful.

A question is "resolved" when atleast one answer is marked as helpful. "Opened" question is a question which

has no answers marked as "helpful".