In the LancerQuest search box (link is below), search the book of the Bible you need plus the word "commentary" (ex. psalms commentary) in the Search Term box to the right of "Title." 
In the left panel of the results page, click on the box by Grace College and Seminary Library to limit results to items available to Grace students, then click on the box next to eBook. 
The results should then be any electronic commentary you have access to on the book you searched.
