To add multiple domains to your Cloudflare account:
Log in to your account.
Go to My Websites.
Add your sites in the Add Website box. Be sure to separate the sites with commas: domain1.com, domain2.com, domain3.com, etc.
Note: You will still need to complete the setup process for each domain (see steps 2-4 in How do I enable Cloudflare on my HostPapa account?).
Click Continue Setup once the domains have been added.