Just click on the Sinclair Infoseek link on the homepage. This will take you to a search page. Simply enter the information you are looking for in the left pane and the category that you wish the engine to look in the right pane. For instance, if you are looking for books written by Robert Speel, you could enter "Robert Speel" in the left pane and select books from the categories on the right.
You will presently be selected to all related material available for the author "S. Robert Speel".
There are a few more advanced search options available to help you filter and narrow down your search. These are listed on the Infoseek page.