in the header.html file you can put multiple attibute tokens which would result in multiple dropdown lists allowing you to 'filter' on whatever combination of values you selected in the dropdowns

example: you have two attributes defined Size and Color. In the header.html file add tokens like this
[ATTRIBUTE:Size][ATTRIBUTE:Color]

Now, in the header you will see two dropdowns, one for Size and one for Color.  If the user selects 'Large' for Size and 'Red' for Color then only items that have both Large checked off as the Size Attribute and Red checked off for the Color Attribute will be shown.  See the pinned post at the top of this forum for a detailed walkthrough of using Attributes