The first thing you need to is create the product attributes and the options for each attribute:
- Go to "Product Attributes" under the "Catalogue" section in the admin (/admin/catalogue/productattribute/)
- Click on "Add Product Attribute" and give the attribute a name, such as "Height" and a code and choose "Option" in the "Type" dropdown list. For the "Option Group" click on the plus symbol.
- You should now see a popup which allows you to add the possible values for the attribute. For example, "Short", "Medium", "Tall" etc. After clicking save the popup will close and you will now see a value for "option group". Click on save to create the product attribute.
- Repeat the above steps for each attribute you want to add.
You can now add these attributes to your products on the "Product" admin screen (admin/catalogue/product/x) under the heading "Product Attribute Values". For example, to add a colour to a product select colour from the "Attribute" dropdown list and choose which colour you want from the "Value Option" dropdown list.
Bear in mind it generally makes sense to add attributes to non canonical products, i.e children products or variants as they are known in Oscar. So if you had a Metallica T-shirt in your catalogue that came in 5 different colours and 2 sizes, you should create one parent product representing the t shirt entity that will be visible when browsing your catalogue. You should then create 10 variant products, one for each colour and size combination, i.e Black Small, Black Medium, Red Small, Red Medium etc.
I hope that makes sense.