In the future, please click on the Ask for Help button located on the challenge. This will create a post and automatically put your current code and a link to the url challenge. It will also allow you to ask your question too.
Watch for case of the id. Footer is not the same as footer.
As far as the last error, I can not see the code which is located below where you ended your screenshot. Just copy/paste your code into a reply, so we can see it.
To paste a code block into the forum, you must precede it with a line of three backticks (not to be confused with three single quotes which is incorrect) and follow it with a line of three backticks to make easier to read. See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (
</>) will also add backticks around text.