Each of the yearbooks is a searchable PDF document.  Open the yearbook by clicking on the picture of the cover or icon; Press the Control Key and the Letter F key at the same time.  A search box will appear in the upper right corner.  Type in the text that you would like to search for (Ex. a person's name) and it will search the document and show each time that text is found.  Click enter to scroll through and find all of the times that it is found.