How do I search for materials when I don't remember the title?

Think about keywords about the materials. Then, try a search by switching to Advanced Search on the [Bib Search] tab and entering the keywords.

If the search has an excessive number of hits, you can narrow it down with the [Classification] item from the [Refine Your Search] menu displayed on the left side of the search result list screen. In addition to using the classification item, you can also narrow down your search by material type, holding library, author, publication year, classification, subject, publisher, language, etc.

If the keyword search is unsuccessful, try using Search by Classification in the lower part of the [Bib Search] tab.

For example, suppose you are searching for statistics-related materials. From Search by Classification, you can narrow down the search to the materials in the following fields by selecting and performing the search with
"4: Natural science -> 41: Mathematics -> 417: Probabilities. Mathematical statistics."