If you have a question about a specific challenge as it relates to your written code for that challenge, just click the Ask for Help button located on the challenge. It will create a new topic with all code you have written and include a link to the challenge also. You will still be able to ask any questions in the post before submitting it to the forum.
the button will show up if you try the challenge a few times (3 times) and fail.
It is hidden to discourage people from asking for help prematurely when they haven’t tried to work on the challenge a bit.
Can you clarify if you are testing before or after adding the media rule?