Once you have the topic you want to teach (and which you love to learn and teach)
decide how you are going to deliver the information you want to share
the decision is based on what is your preference. Decide to begin with the style you are most comfortable with, one which comes easy and will not hinder you in being who you are while you teach and share your topic.
in my case it is video and here is a quick tutorial I found on YouTube for you.