To create product options, click on the Product options tab

Example 1: Options without extra cost:

Example 2: Option with extra cost:
Select: Add product-as-option

Note 1: Remember to create the option products as well, even if you don’t sell them individually, so your warehousing stays in order. Remember to select the Only with main product option for these products

Note 2: You can change the order of the steps by moving the cursor over a step and holding the mouse button while re-arranging the steps