The pictures on this website are protected by the laws on intellectual property. In law, they are the property of their author. They require personal skill, equipment, time and money, and their author can make a living out of them. Taking and distributing them without consent is a form of theft and can be prosecuted, even though the author is not a professional artist.
The fact that these pictures are put on the Web gives you no right on them. Without the author's consent, you cannot make a commercial use of them, i.e. reproduce them in any commercial document, printed or electronic. Also, without consent, you cannot make any profitless distribution, such as, for instance, putting them on your own Web page.
In order to get the author's agreement, contact him and explain what you intend to do; the agreement will cover this use only. Depending on the case, it will be given for free or you will have to pay for it.
Thank you for your comprehension.