How to add your product size(s) in osCommerce template ?

 We are going to show you how to add sizes to your product 
 1. Go to yourdomain.com/admin/login.php 
 2. Enter Username and Password to login. 
 3. Now select Catalog in the left navigation of the page. Select Products Attributes. 
 4. To add a size you have to create one first. We'll create two: 38 and 39. 
 5. In option name choose Size.
 6. Then enter option values 38 and 39 and click insert.
 7. Do the same for your next sizes. 
 8. 2 sizes have been added. 38 and 39. Now we'll add these two sizes to your product. 
 9. Choose product where you want to add available sizes. 
10. Select what you want to add to this product. In our case Size. 
11. Select option value. 
12. there will be 38 and 39. 
13. Choose which you want. 
14. When you're done click Insert. 
15. Other operations about size inserting are the same. 
View video tutorial below to make thing more clear.