Spend some time freewriting about your discourse community. This can be anything you want. You could...
Find a partner to work with. Tell that partner who your discourse community is, and ask them to tell you what they know about that community. Then switch and do the same for your partner. Here are some examples of questions you could ask:
My discourse community is xxxxxx. What do you know about this group?
When I mention this group, what comes to mind?
What kinds of things do you think people in this community talk about? What conflicts might they have?
Within this group, who do you think would be an authority? Why?
Have you heard of any stereotypes or generalizations about this group?
Feel free to ask other questions that help your partner think about their discourse community.