It may not be obvious, but that file has three other royalty-free textures as well -- bonanza! Read on for more info and some critique.
How to use this image? Like any other detailed photo, I recommend ramping down the contrast. Then use it as a layer with the mode of your choice. Try Multiply, Screen and Overlay first. You can also modify the image by giving it a good blur. And don't forget to try stretching it and zooming in to find areas of particular detail you may want to use. Experiment and have fun!
Though I'm grateful to be included, I must comment on the quality of some of the entries. Many are very nice photos but are not useful as textures, that is, as images to apply to a base image in order to get to a finished work with more detail or depth. They are far too finished in and of themselves. This was not a contest for still lifes, patterns, intriguing abstracts or general-purpose stock photos. But it sure looks like one.
Even "Seeds" tends towards this itself. It is telling that this particular photo was chosen out of the four in my pack. In some ways it is the least useful.
By way of explanation let's look at the editor's favourites. I can see three major things wrong with the choices here. By explaining these I hope to give you a better idea of some of the thought that goes into creating textures, a process I'm engaged in actively at the moment. I'll use some specific examples but photographers do not take this personally!
The choice seems to have been largely swayed by colour, and yet textures are rarely used for their chroma information. How many of these photos would look especially interesting desaturated? For example does the "shocking-red container-ship" have much texture at all?
The second criteria: How much low-level detail is there? You might wish to use a texture in a rather abstract way, to add a sense of depth and dimensionality to your work. Fine detail, as opposed to the overall geometric shapes, is important here. For example, I do not consider "Light trails" to be a texture at all. Instead, take a look at "Cracking"; it has a lovely blue tone but also great contrasty detail.
The third issue is one of perspective. The most useful texture photos are those which are taken flat on, so there are no perspective lines. (Though they might have some depth within that plane -- in fact this can be a real boon.) If one wishes to add perspective or otherwise distort a texture, it's easy enough to do. But not so going the other way. Besides the extra work, image detail will be lost. The shot from Tom Karels & Ryan Beals is a nice photo but almost completely unusable as a texture. Unless your work is screaming out for a highly geometric overlay sloping off into the distance at exactly that specific angle.
Here are the other images included in your free texture pack. Let me know if you end up using them. Each links to the Flickr page so you can send me comments. Sign up as a Contact so you can see my progress. More details as the texture set evolves!