This is for those who have already signed up and point their Nameserver to Cloudflare.
1) Go to https://www.cloudflare.com/ and login to your account.
2) Select your domain and click on DNS.
3) On the bottom row, and a new A record to point the domain to IP address, click Add.
4) Add another record, select CNAME and point "www" record to the designated record, click Add.
Make sure there are no other CNAME or A records for 'www' or www.yourdomain.com, otherwise there will be a DNS conflict.
If you're planning on using Cloudflare's CDN then you can leave the TTL settings as Automatic, otherwise set it to to 2 minutes.
5) You can toggle the utilization of Cloudflare's Content Delivery Network (CDN) by clicking on the cloud icon under the Active column.
We would recommend enabling Cloudflare's CDN for improved response time globally, higher stability, and rock solid security.