1. Download rainmeter from www.rainmeter.net (If you don't have it already).
2. On the right side of this page is a green arrow pointing down with the text "Download File" next to it, click it to start download.
3. Once completed the installer will run automatically (If not go to your downloads folder and run it from there).
4. If the skins don't load automatically, right-click the rainmeter icon in the taskbar and chose manage, go to the layouts tab and find the new layout (If it's not there load all skins manually and move them to the right place or anywhere you want them to be).
But since this skin is in a rar file you will also need a program like winrar or 7-zip.
After downloading this skin open the rar file and extract the folder to "My Documents\Rainmeter\Skins", then right-click the rainmeter icon in the taskbar and chose refresh all, then proceed to step 4 in previous instructions.