You need to open the .htm (or .html) file for you homepage of your site (normally index.htm or index.html) in Notepad.
First you want to make a copy of your file. Click with the right mouse button and select Copy. Now, click a blank space in the folder and click Paste. This will create a file called "Copy of.....".
Now, open your original file in Notepad. Easiest way is to click with the right mouse button on the file and choose Open With... and then select Notepad.
This will open your webpage in code view (html code). Now, copy and the counter code as per the instructions (points 1 and 2).
Now, find the section of the code in Notepad which says "/body>" (without the ""). Place the cursor before "/body>" and paste the code you have copied.
Now, save the file and upload to your website.
The counter should appear at the bottom of your page.