When using FreeMarket, you may include up to 4 URLs for images. While your item is listed in the NXT blockchain, the images are not, and therefore they must be uploaded to some location on the internet, and then that location, in the form of a URL, may be included in your listing.
The blockchain preserves your privacy, but the location of your item's images may inadvertently reveal your identity, so it is important to upload your images to a location that will preserve your anonymity. There is a variety of services on the internet that will anonymously host images for you. You will need to do your own due diligence to determine which service you trust. Some of these services are listed below, but their inclusion here is not an endorsement. Remember, only you can preserve your own privacy.
Only use services you are confident you can trust. If you do not know what you are doing, then do not include images in your listing
Images should be 200 pixels by 200 pixels. Images with other dimensions will be resized to 200x200 for display.