You do not have to add a pic or video. But it's a good idea if you can.
The problem you are having most likely is not putting any tags in the tag box.
So if your post is about dogs for example you would put one word tags - all lowercase with no spaces - such as
pets dogs cute caring sharing
That's just an eample.
You can also put #dogs in the article and it will just add it to the tags, but 5 tags are the max that are all relating to your post.
Hope this helps
Thank you for this info. I was spacing the tags, but I put a comma after, and it wasnt working, so I fixed it. :D