Customers can select options when they see a configurable product, e.g. colour or size. This is useful when you want them to click on a generic product name and then tailor the product to suit their needs.
The first thing you have to do is create any new attributes you require. After specifying the values for these, you then create a new attribute set. Drag the new attributes into a new group called Selectable Options.
Next, you create the configurable product. Select the new attribute set and then select only the options you wish to include for this product. You can see by doing this that you could have one attribute set per configurable product type, or you could have one configurable product for all products in the shop.
After doing this you can assign simple products to the configurable product by clicking on Associated Products and selecting them. If the simple products don’t appear in the list as expected, then it’s most probable you either haven’t set the attribute scope to Global (required for all configurable product attributes) or you have assigned a different attribute set to the product.
Rule #1: Attributes used in configurable products need to have a global scope.
Rule #2: Simple products assigned to configurable products need to be assigned the same attribute set.