In the upper right of the wiki page, there is a search bar that can be used to find pages either the NPL wiki, or across all wikis. This searches titles of pages, so as long as you keep the terms general you can find most pages.
Search by label
You can use the 'labelText:' prefix to search specifically for content that has a specific label. For example, if you're looking for pages with the label Helicon Focus', type labelText:Helicon Focus into the search field in the Confluence header.