The forum is divided in the structure as below :
Categories and forums are designed to organize the discussions that people have in this forum and are not modifiable by users. Topics are created by users under relevant category and forums in order to initiate a discussion or showcase their work.
In order to create a topic for discussion, select the appropriate category and forum. Then click on the "Add Topic" button.
Then you can add the topic title and content and click "Add Topic" again