The simplest way to write MathML is by using the Wiris Editor in BluePrint.

When you are editing a piece of content in BluePrint (like a lesson, question, or flashcard), you can click Visit Wiris editor site at the bottom of the content box to launch the Wiris editor:

This will bring you to this page on Wiris.com.

After you write your math equation:

1. Copy the equation/formula inside the white box
2. Return to your content item in BluePrint
3. Click Source to show the HTML
4. Paste the MathML you copied into the relevant spot in your content
5. Click Save 

Your MathML will now appear, formatted, in your content.