I set the font size to 36 for the Welcome sentence and 18 for the Glad sentence, however after I save and view the page, the font size is very small. What am i doing wrong?

http://www.classcreator.com/WoodlakeVillas/class_admin_pages_form.cfm?custom=0&rr=58359

I can't see that page but your home page has redundant/multiple span class="mainfont" following the initial 36 font size def. Those later definition reset the 36 font size.

Put the editor in source mode and remove those lines from span to /span.