Now you would like to start a discussion
After you have chosen an appropriate category, you will find a “New Topic” button at the top and at the bottom.

You will get a form similar to the Reply box with few more elements (text fields).

Subject : give a subject to your discussion (relevant of its content)
Similar topics : If you wish to link to other topics to get a better understanding of your own message, enter the numeric ID of those related topics ( How to retrieve the numeric ID of a topic)
Sub-category : choose a sub-category where your topic should belong.