Start at this link: https://browzine.com/libraries/825/subjects. Choose Seton Hall University the first time you go to this site and you are on your way. You can also download the app for your phone. Nonprofit Journals can be found under Business and Economics -> Management and Nonprofit Organizations.
JSTOR is database that contains scholarly articles from many disciplines and subject areas. Much of its content is available in full-text (although full-text of recent articles may not be available for a year or more).