How can I use Cloudflare on my Domain?

Cloudflare is a CDN (Content Delivery Network) that makes your websites secure, fast, private and reliable. It is a performance and security service that allows your website to load twice as fast.

Cloudflare also offers excellent DNS management for standalone domains that do not have hosting. Cloudflare has both free and paid plans. The free plans are excellent. You need to sign up for Cloudflare to be able to use it.

To signup:

Simply fill out your email and a password, and tick the checkbox to accept CloudFlare's Terms and Conditions.
Then click on the Signup button. The system will create your Cloudflare account, and you can link your domain to it
Click on the Domains icon and select the domain where you wish to activate Cloudflare.
Once selected, click on the "Provision domain with CNAME setup" button.
Once the Cloudflare system is active in your domain, you will see the Active status. Also, you will see the cloud icon in orange (which means active) for your domain name entries.
If you wish to activate any other subdomain entry to go through the CloudFlare network, simply click on the grey cloud icon for that subdomain.

Since CloudFlare changes the CNAME record of the www subdomain only, you will also need to redirect traffic from mysite.com to www.mysite.com

For more information, you can refer to https://developers.cloudflare.com/cloudflare-one/tutorials/