You can be able to talk in main chat only when you have a forum like like NCM, JCM , RCM , SCM etc ...
You can get these ranks by applying for them at this
board , before submitting an application make sure that you have all the required requirements that are written in
here, Furthermore, you can get NCM rank by making a
request in here , and you should make at least 10 posts so they can consider you as an active forum member.