When you want to REPLY to an existing discussion or answer somebody else's question you need to Post A Reply.
Posting A Reply:You will probably be reading the original post already
At the top of that page there will be a button that says Post Reply - Click that button
A new topic editing area will open...
You do not need to add a description in the Subject Bar - it will be taken care of when you hit Send.
- Add text in the main editing area
- Click Preview to make sure the post looks like you want it to
- Click Send when you are finished