You can inquire at the Reserve Desk on the main floor of the library or refer to the list of electronic and library-only resources that have been placed on Reserve by instructors: http://www.lib.uidaho.edu/index.html
All electronic files will appear at the top of the list and will show ERESERVE as the call number. You may need a password (supplied by your instructor) to access electronic files.
Print are located behind the Reserve Desk and may typically be borrowed for 3-hour periods. Check the link to the specific item for more information.