I need Bible commentary on the first half of the Book of Joshua. Where would I find that?
In addition to a quick "discovery" search for materials on the library home page, try searching in the religion modules from EBSCOhost's All Reference Databases (put check marks next to Academic Search Complete, both ATLA modules, and Old Testament Abstracts) and from the Oxford Biblical Studies, located in the eBooks section of the library's site.
All three provided excellent materials for your search. I've attached permalinks to an eBook and an electronic journal article we found from the "discovery" search as links. In addition, you'll find the EBSCO search history and a sample chapter from the Oxford search attached here as files.
In addition to simply putting in a natural language/keyword search (Book of Joshua), also try running a Subject search for "Bible -- Joshua -- Commentaries" for more materials.