Well you can use those for circulating air within your tent, but for cooling your light you should get an inline fan or something with an enclosure around it. The exposed blades on those fans are going to do more harm than good if you try and put them in flexible ducting like in your tent.
For mounting those within your tent, you're probably best off going to your local hardware store and bringing one with to see if they happen to have compatible mounting brackets, you could try finding something online but you might end up buying something that doesnt attach properly, so thats not really a good way to go, you'll end up wasting time and money. If your hardware stores don't have a solution you can try tracking down the manufacturer to see if theres replacement brackets available, but if thats not an option unfortunately the only other way is DIY.
If you could post a pic of the back side of the fans where they're supposed to attach to the bracket maybe I can help you figure out a DIY solution if you'd like, the pics available its kinda hard to tell how those are supposed to mount.
Good luck with your first grow