May i know how to implement content delivery network for a website.

You can use Cloudflare. It is free and easy to deploy. Just let it manage your DNS and it will act as a wall between your website server and visitors. Visitors will access to Cloudflare nearest server and Cloudflare will fetch the content of your website and cache (static content).

Yes cloudfare is one of the free cdn network available. If you are using wordpress you can also use the wordpress free cdn network using jetpack plugin.

cloud flare is the stat of the art technology

I have used Cloud Flare. This will help you to attain this.