On the homepage of CCleaner, click on the link at the top for Download.
The download section will provide you with several links to download from mirror sites, click on Alternative Download as that downloads directly from the website of CCleaner, but you can download from a mirror site if you wish.
If downloading from the Alternative link, it will take you to a page saying that it will begin downloading in 5 seconds, if the download window does not popup (as a result of a popup blocker installed on your computer) click on the link that says Click here if it does not [automatically start downloading].
When the download prompt appears, click Run.
If a security warning appears as a result, click Run.
When the program starts the installation process, choose English as the installer language
Click Next to begin the installation.
Click I Agree on the License Agreement screen.
Choose a destination folder for the program to reside, or use the default and click Next.
The next screen displays the Installation options, I recommend leaving all options checked for ease of use, then click Install.
When the download prompt appears, click Run.