<head> section of your web page as shown below.
If you need support for IE6, 7 or 8, you need to include some polyfills. See details in System Requirements.
Highcharts is already included in Highcharts Stock, so it is not necessary to load both. The highstock.js file is included in the package. The highmaps.js file is also included, but unlike highstock.js, this doesn't include the complete Highcharts feature set. Highcharts Stock and Highcharts Maps can be loaded separate files like this:
<script src="/js/highstock.js"></script><script src="/js/highmaps.js"></script>
But the separate files can't run in the same page along with each other or with highcharts.js. So if stock or maps are required in the same page as each other or with basic Highcharts, they can be loaded as modules:
<script src="/js/highcharts.js"></script><script src="/js/modules/stock.js"></script><script src="/js/modules/map.js"></script>
You are now ready to use Highcharts, see Your first chart to get started.
*) Highcharts version 1.x relied on excanvas.js for rendering in IE. From Highcharts 2.0 (and all Highcharts Stock versions) IE VML rendering is built into the library.