Creating Own Test Steps

Hi, I am attempting to add onto the custom email test step created in a previous article. The question I have is one, how to add a run button to this custom step. And more importantly how to all this step to access data from other steps throughout my test suite. Currently my step is up and running allowing four recipients and two attachments, but I want to be able to add data from previous steps to fill the message content in the email. Thanks!