You will need to access your website DNS account (with your DNS provider/registrar) to update the "A" record for your iMIS website(s) to point to the WAF IP address (provided in your email notification).
If you aren't sure who your DNS provider/registrar is, you can go to https://mxtoolbox.com and search on your website domain (ex: Advsol.com), selecting the "Whois Lookup" option. Those results will tell you who hosts your DNS. That is who you need to contact to let them know that your website should now be directed to this new IP Address.
Example of who our provider (or Registrar) is below: