The search phrase goes into the search box.
Tap the symbol in the top left corner for the menu, then customise any of the following:
(Please note, in tables, a tap selects the item, while a long press starts editing)
1. Search Engine
Google is of course the most popular, but some people prefer other ones. You can also add your own.
Select or add a site which holds your desired information. The search engine will then only return results from this site.
3. Helper Phrase
Select or add a helper phrase. This can help streamline your search.
You can add phrases, such as 'iOS Cocoa' for example, to get only the stuff that is related to iOS development.
You can also exclude stuff by prefixing it with '-'.
Other search engine parameters should also work as they are simply passed to the search engine. Check the help of your preferred search engine for details.
Go to History to view and recall your previous searches.