HI Preston,
So you just need to add some fields to your app UI and then use these fields to make body of your message.
In this case you need:
1 Add needed fields to the APP.
2 Open "Before send" mapping for sendgrid service datasource.
3 Find needed parameter for example body.
4 Click "JS" button on this parameter(to add JS code).
5 Populate it with JS code code like:
pre
//Where "firstNameName" is a goal field name.
var firstName = Apperyio("firstNameName");
//Where "secondNameName" is a goal field name.
var secondName = Apperyio("secondNameName");
var goalStringToReturn = "Hello " + firstName + " " + secondName ;
return goalStringToReturn;
/pre
This is a simple example that describes how you can use all fields that you need and combine them into single string..
Regards.