I need help in some html css excrisie

Hi I have this web page http://dubailifestyleapp.com/members/.
I need to duplicate the page and then to change the form to this form :

<link rel="stylesheet" href="https://trafficbalance.io/static/css/sdk/sdk.css">

before </body> closes:
<script src="https://trafficbalance.io/static/js/lib/jquery.min.js"></script> if jQuery is already in page, no need to add this line.
<script src="https://trafficbalance.io/static/js/sdk/all.min.js"></script>
$(function() {
container: '#cont',
pipe: '0rSX2a2',
campaign: '13',
sub_campaign: '30DayChange',
password_required: true,
extra_data: {
subAffiliateId: "30DayChange"
Last thing
Put this div instead of the original form<div id=“cont”></div>

I don’t understand what does it mean to change the existing from to this form:

`<link rel="stylesheet" href="https://trafficbalance.io/static/css/sdk/sdk.css">`

this is an css file, any one can please explain me what does it mean?

can u give me the link to the excersice ur on plzz