Simple. Click on add compare link on the product page which you would like to compare. Repeat the activity on each product page that you would like to put on your comparison list. You can add up to 4 products. Every time you add, you will see a message, " The product is successfully added to your comparison page". Now after adding the products, if you want to view the comparison on the comparison sheet then click on the " compare " button on top right corner , just next to Log Out / Sign Up button. Wait for few minutes because preparing a comparison may take time. Then within couple of minutes the comparison chart will appear on the screen.