May I point out these quotes in the FAQ section from: http://www.wipo.int/copyright/en/faq_copyright.html
"Can I register copyright?
In the majority of countries, and according to the Berne Convention, copyright protection is obtained automatically without the need for registration or other formalities."
This means that If you are the original creator of a work, then you automatically have copyright over it.
Did you even read the FAQ section?

Also "What is the © symbol? Do I need to include it on my work?
In the past, some countries had legislation in place that required the copyright holder to comply with certain formalities in order to receive copyright protection. One of those formalities was to include an indication that copyright had been claimed, such as by using the symbol ©. Currently, very few countries still impose formalities on copyright, therefore the use of such symbols is no longer a legal requirement."

This means that just because it is out there on the internet you cannot use it without licensing it.

The most common licensing is creative commons, and the best for images if you choose to use them is CC0 (which means the creators have given permission to use the image in any way without attribution).