Joanne - see my answer below.
Assuming you are creating a topic for entire Wohaula.
1) Click on Topics -->Discussions.
2) Click on the button "Create New Topic"
3) Type up your topic.
Don't forget to choose a category.
Click on Save. Your topic is posted.
Assuming you want to post a topic for your group.
Here are the steps.
1) Click on Community --> Groups
2) You will then see Wohaula Group List page. (like below)
Click into the group you want to start a discussion.
3) You will then get into the Home page of that group.
Click on Discussions on the left bar.
4) You will then see a page like below. Click on Create New Topic.
5) Then all the steps afterwards are exactly the same like you just learned.
Type up your topic. Choose a category. Click on Save.
You are all set.