go to site (www.cloudflare.com) and open free account, also you can utilize this via your CPanel (depending on if you are hosting moodle with third party, and they have given CPanel as hosting administration panel), you'll find all cloudflare options there (like shown below)

if you dont have CPanel available, then still you can route traffic through CloudFlare, all you have to do is, create free account there, and add your website (rest follow their instructions), you will have to make changed in your domain's name servers to utilize the CDN.

Just be aware, that start with all basic options (means everything turned off) and gradually start turning on the things like Cache parameters for HTML, CSS and JavaScript. in about 2-3 days re-test your website once it has propagated most of the content on to its nodes and see if it makes the difference.

For second option, you have to ask your hosting provider, as you definitely wont be using a shared host for 13,000 users, it will be a VPS or Dedicated or Cloud.

Though, start with CloudFlare, see what difference it brings to your site, if you are having difficulty setting up properly, gimme a shout and i'll guide you through properly.

Hello Visvanath,

They are hosting on BlueHost, their DNS's so far fastest in shared hosting industry as far as I am aware of and have tested, stuffing 13k users will take equal share of bandwidth where they have given reference to the front page score showing nearly 10MB of loading scripts and images, also their prime location for accessing the site is Saudi Arabia and once can expect loading time increasing reaching destination, so have recommended dedicated bandwidth plus use of a CDN and optimization of frontpage. I had done load tests prior recommending and load tests came out fine, only making the rendering of client side scripts as major cause of these scores.