Adding explanatory text to Event Registration form WCM

We have recently upgrade to iMIS 15.1.3.8845 from 10.6 and setting up our website with our first event.  On our Create New Account form/page, we have included a number of user defined fields from cutom tables we have in iMIS, demographic questions, options to opt in and out of certain things, etc.  For backoffice deskstop use these fields and their labels make perfect sense to us, but on our form we would like to include some text to explain these more fully.

Does anyone know how we can insert text at selected points on the form?

Failing this, we were thinking we could use the PROMPT field in the user defined tables to add some explanatory text.  Unfortunately, this is limited to about 30 characters.  We have looked in vain to try and find the table that holds the prompt data, to see if we could directly enter more into the field in the table?

This worked perfectly for adding long questions to our event registration form.  The WCM would only allow an entry up to 100 characters but in the table we can enter much more.

Thanks