when you download them to whichever folder you intend to save them to, open photoshop. Go to EDIT PRESET MANAGER and make sure the drop menu in the box that opens says "Brushes" and then all you have to do is click "Load" and open the folder you saved the brushes to and click the brushes file and it will automatically load the brushes to your PS program. ^_^
Check out my bird brushes and read the reply I gave to ElfDaughter about the same question just using different brushes. I will make a tutorial because apparently so many people want to know how to do it and I guess it's not as easy as it looks, lol.
Hi, this is Belladona-Stock, this is my main account. I would be thrilled if you wish to use any of my brushes for commercial use, just please be sure to credit me in some small way and send me a link to your final product so I can see what you've done with it.