First of all, you have to download EqualizeCss in any convenient way.
$npm install equalizecss --save
$bower install equalizecss
$yarn add equalizecss
Or just download .zip archive with repositoryDownload
Add to project
After downloading the grid, you need to enject it to your project. It's very simple - just add production (equalize.min.css) or development (equalize.css) version between <head> and </head> tags of your .html file. I strongly recommend connecting the EqualizeCss before other styles (.css) files.
<link href="css/equalize.min.css" rel="stylesheet">
<link href="css/equalize.css" rel="stylesheet">
Also, don't forget to include viewport element with recommended parameters in all your .html files. Read about viewport meta-element here.
<meta name="viewport" content="width=device-width, initial-scale=1.0">