In Explore, under the Communities tab, you can see every community that is currently active in Lynkos.
If there is a particular one you are interested in, you can enter and see the threads that have been created for it.
If you participate from a community or follow a thread, you will receive notifications whenever someone creates a new thread or comments the thread you are following. Also, when you Participate in a community, you will automatically start following the threads of that community.
Once you follow a thread you will be able to leave a comment.