I’m a newbie as well, but I visited the Knowledge Base when I started and I found a few links that might help you!
Some errors are just warning flags, you need to determine if each one is relevant to your post or not. Once you’ve determined that the item is “ok”, check the error off the list. All items must be checked off before you can submit your piece.
Also, per Newslines:
Please note that INVALID posts HAVE NOT BEEN SUBMITTED! You must fix the errors and/or check the checkboxes to submit your post fully. If your post is on THIS LIST it means it has not been submitted yet.