So it sounds like you are kinda stuck at the beginning then.
Here are some hints:
You need to write your own HTML code to post the given password to the website. You can then paste that code within the webpage and submit it. After you do this you will get an invalid CSRF error because you also need to submit the token along with the password.
You can look at the POST method already included in the source code for hints.
You need to figure out how the playground sends POST requests - the first challenge (Intro 1) has a good example that uses the same token. Look at how the information being ‘sent’ is formatted in the POST requests e.g. name=“name”