First, please visit the following link:
https://www.netflixparty.com/support to ensure the device you are using meets the necessary system requirements. Please note, everyone that joins the party needs their own Netflix account. An account will note provided to registrants.
Next you will need to install the Netflix part extension on your browser. Please visit the following link to do so:
https://www.netflixparty.com/support. NOTE: This needs to be downloaded on a computer not a smart phone
Finally, please review how to join an event here:
https://www.netflixparty.com/support.