To add your own search, follow these steps:
1) Tap Edit
2) Tap Add
3) Type in the page to which you want to add your search. Let's say you want to add a search on gamefaqs.com. Here type in http://www.gamefaqs.com and click Search.
4) We will now navigate to the search box on the gamefaqs website. Here enter Asdf as your search and search for it. Asdf will be used as a trigger to tell WebSearch where to enter the search criteria.
5) As soon as you search Asdf, WebSearch has what it needs. Now it will ask you to name the search. For the gamefaqs example, we will name it "GameFaqs" (without the quotes).
6) Once named, the search is present in your search list at the bottom. Feel free to reorder the searches as you see fit.