You use the search box on the header, enter the keyword and click on [Advanced Search] on the left. The drop down menu on the left of the search box gives options to target things like [All> Documents, Discussions].

If you need to change how the search result is sorted, please click on [Advanced Search] (shown in the figure). From there you can change the sorting from the [Search Results Sort] field and choose from the drop down menu. After it is all set, the result will be shown as set.