These I didn't make into tiles myself, so essentially they are just the photo. That allows the user to decide what to do with it's use, but if you do want to make a chunk of the image into a repeating tile (good for web backgrounds) and don't really know how, there are some software options available that you can use.
Pixplant is one I have used before; others are options like Patternizer's striped pattern generator, and PatternIco for doing it online. There are many small freeware products out there for doing this - at one point I had half a dozen installed and they all produced something slightly different, depending on the design in the original photo. If all you need is to make a basic tiled web background, any one of the free products would probably do the job just fine.
Personally, I just use Photoshop since I own that product. It does the job, but sometimes it takes a lot of fiddling to get it to tile seamlessly.
For using textures in 3D software you generally do need to have a seamless tile ... although I haven't used a 3D software in about 5 years, so some of the functions may have changed since then. Anyone who uses 3D imaging programs regularly will probably already know how to turn these into useful textures for the program's use. It only takes a small bit of an image (256 X 256) to make a texture that will work on 3D objects.