Can't get "Closed" issues to be removed from "Open Issues" list

[Darren Amundson [Administrator]]

I didn't set up the workflow and schemes, but that person is no longer working on our bugs/issues and I have inherited it..   What can I read so that I understand how issues and schemes should work.  I see a workflow diagram..   My main problem is that when we "Close" issues they stay on the "Open" issues list.  Secondary problem is we can't order the issues by priority.  Even when we select to sorty by priority, we still see all the issues, even closed ones and they are not in order of priority...