@abdadiamaljrushi, some answers;
1 - You just posted on one of the forums. There are a few and depending on your question, that’s the forum you’d post to. For instance, if you’re just starting the RWD course and have a question/problem with one of the lesson you click on the Ask for Help button. That will post in the HTML-CSS forum. If you’re working on one of the projects and have a question you can ask in the ‘Cerfification Projects’. If you’ve completed one of the projects and would like feedback from the community then you can post in the ‘Project Feedback’ forum. Look around and you’ll get a feel as to what each of the forums is for.
2 - This is a problem that it seems many people here have had. If you search the forum for “mocha div missing” you will find many posts and many solutions. One of them is that you have to add codepen.io to the list of allowed third-party website cookies.
As an aside, the link you posted is the one for FCC’s pen. You would copy the URL from your project in codepen and post that link.
Welcome to the forums and happy coding.