How to get my PUT_LINE statement to display in TOAD?

You need to enable DBMS Output. If working in the Editor right-click and choose DBMS Output off of the Desktop flyout menu. There's a button that is red if it's disabled. Click it and it will turn green. Then execute your code. Output will display there. If you are working outside of the Editor (in Schema Browser for instance) select DBMS Output off of the main Toad View menu. Enable your output there. Output will display in that window.