For something like this, I think merge fields would be better.
You'll need to create the fields first, if you haven't aleady done so, and then add the text/merge fields to the layout. Use the Text tool to type the plain text parts and when you get to where a merge field is supposed to go, press Ctrl-M to bring up the dialogue, select the relevant field, then keep typing the rest of the text parts. Eventually the text and merge fields will all be in one "text block" on the layout. It should look something like this:
This contract was created on <<date_field>> for the purpose of <<purpose_field>>. The buyer is <<buyer_field>>.
Calculations also work. Which is best often depends on what you need to do with this message.
"This contract is created on " & Table::dateField & " for the purpose of making green eggs and ham. The buyer is " & Table::BuyerNameField