From a cursory look, your markup structure looks pretty good. A few immediate thoughts:
You’ve got two <header> tags - the second one needs to be turned into a closing tag for the markup to work as expected.
It looks like you’ve got an extra closing </p> before the second <header> tag.
Looks like you’ve missed out the date/time.
The sentences on the same lines as the <h2> elements need to be inside their own paragraphs
You can see all you need to do to complete the assessment on our marking guide:
Probably easier though is to just check your markup against our finished version:
Don’t get worried if you structure is not identical to ours — there are multiple ways to do each task in web deveopment. We didn’t include <section> and <article> elements in our version, but you’ve used yours well, so that’s fine.