If you don't know where to put "Browse by Make" and "Browse by Type" logo images, please follow this guide.
Icon Filters element on the Classified layout Home page displays Listing Category logos/images. And these images don't come with a demo import.
In order to put these logo images, you need to go Dashboard > Listings > Listing Categories and be sure that "Use images for this category" option is enabled for this category. Then click on Manage icon on the listing category:
And here you can see the list of Categories. You need to click on Edit link and then you can see the Image field where you can put the logo images: