You probably have the commercial or business paid versions already, that is needed.
I think they updated the options/characteristics page listed above after my posts a week ago. it now makes sense. follow it step by step and it does work:
Options enable you to propose to your customers additional options for a product. For example, if you sell computers, you could ask your users whether they want more RAM, or a bigger Hard Drive Disk by paying a bit more. The total price is then updated in live so that the user can see the full price of the product + the options before adding the product with its options to his cart. Note that an option can only have ONE characteristic which will be displayed as dropdown on the main product page.
•Add button : You can add an option by clicking on this button. That will displayed a popup with the interface to browse your products, select them with the checkbox and click on OK to add them.
•Delete icon: You can delete an option by clicking on this icon.
Please note that those modifications will only be applied when you save the product. Options are only available in our commercial editions.
Before selecting an option in that interface, you will first have to create a new product (which you could put in an unpublished category if you don't want users to see it on products listings). After adding that product as an option to your main product, you will see a dropdown with 2 possibilities on the product page. If you need more or different options, you will have to add a characteristic to your option product allowing you to have one variant of the option product per choice on the dropdown. You can see such options on our demo website:
Let's take the example of the creation of the RAM option :
First, we made one characteristic called RAM quantity with the three values via the menu Products->Characteristics.
Second, we created one product option (like a normal product) that we called RAM and we added that characteristic to it.
Third, we clicked on the "manage variants" of that option product and set the name of each variant and its price.
Finally, we added the RAM option product as an option of the desktop computer product on the desktop computer edition screen.
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