What does that mean when I try to post in forums

you have been ignored by the OP, you may not be able to post on it.  Other than that, I have no idea.

All their posts on all threads will say "users post is ignored." you may have accidentally ignored them. It's easy to do. The ignore button is at tge bottom of all posts right beside "quote," "reply," and "report this post." very easy to hit that button by mistake if you are on a small touch screen phone.

If someone puts you on ignore you can still post to your heart's content. That particular person just won't be able to read it.
"Users post ignored" means you ignored them, not that they ignored you.