Hello Sherry. The first instruction is for Site admins to make sure glossary autolinking is available throughout your site, so you probably didn't see it as you are only working in a course. The glossary instructions are in the documentation on Glossary activity and there is also a video you can check in the documentation page Filters
However, if you feel you have done everything correctly, then one thing to try is to go back into a glossary entry and edit it - even if it's just a tiny edit, or simply open it up and then resave it. Sometimes that 'kicks in' the auto linking.
I'm sorry I don't know what eClass is - but I presume it is standard Moodle.