Linking Attributes to Brands

Hello,

I am working on a spareparts web shop for motorcycles. I would like the filter form to show Brand i.e Yamaha, BMW. If the user selects Yamaha as the Brand they should then see the different Yamaha Models only.

I have set up the models as the attributes and I am not sure how to link the Model to the Product Brand so that the user sees the products of the brand selected only.

The user should not be able to select the Model without selecting the brand firrst.

Please assist.