The participants post box will be located just under the instructional text and look something like this:
You can see in this example, the participant can type in their post and click ‘Add Post’ to submit. Depending on whether or not the activity is influenced or uninfluenced, the participants may or may not see other Posts prior to their initial Post.
You may also notice the camera icon. Clicking this icon opens up a window where the participant can browse their hard drive to upload a picture to the discussion.