Cannot sign in to save progress

HTML-CSS
#1

Tell us what’s happening:
I understand the code. How do I sign in to save my progress??

Your code so far


<h1>Hello World</h1>

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.87 Safari/537.36.

Link to the challenge:

#2