How do I share this with my teacher on itslearning?

Well -

Your Voki can be shared in several ways - but the simplest way is as a link.

Just like you can share any link with your teacher - you can share your Voki.

After you save your character, you are taken to the "publish and share" page

one of the options here is the permalink. Copy the link and share it with your teacher.

Hope this helps,

Gil