The issue here is that the question you want to answer is protected. Questions are protected occasionally because we get a lot of nonsense answers, especially if the question hits the Hot Network Questions list.
In your case you want to post an answer to the question about "Semi" trucks. That's great! If you know something others don't, then please share it. But, because that question has fallen foul of untoward attention in the past, we need to make sure that people who post on it are invested in the site: we do that by ensuring that they have at least one other upvoted answer (which gives the required ten rep points).
It's not OK to edit a post to say it's wrong: that's vandalism and your suggested edits were rightly rejected.
If you would like to invest in the site, please create an answer on an unprotected question which can be upvoted. Once that's happened, you will have the required ten rep points to allow you to go back to the first question.
The "protected question" restriction isn't the only restriction which new users encounter, but it is the most obvious one which causes the most issues. Asking a question about it does allow it to be explained, which could also help others in the future.