If you want to add an extra information about a product, login to Store Admin, click on “Extra Fields” on the menu. Add a new field. Remember to give it a field name without a space. Ex. product_year. Then click button “Add New”
Now go back to product modification/add page, you’ll see this new extra field. The value allows only 255 characters, so you don’t want to type some text longer than that because it won’t be saved to your database.

Now if you want to display this value, go to skin/customer/main/product.tpl, modify some Smarty template codes that is related to this extra field. Use exact field name that you already defined earlier. Save the page. Now go to each product page, you’ll see the value there.