Explain why this statement is incorrect: "if i find something on the internet, that means it is for the public use, and i can do anything i want with it"

This is Copy Right and it means if you change it enough then you can use it.
For example if you were to use an article on penguins in a video as long as it was not the whole video and you had commentary behind said article that would be fine. 

This would be copyright unless you change it significantly.If you don’t change anything you might be fined.

Answer the important painting of the baptism of the christ, leonardo painted the kneeling angel and some of the background for this;

In windows explorer, select the file, folder, or groups of files and folders you'd like to copy. you can select multiple files or folders in several ways: click the first file or folder you want to select, hold down the ctrl key, and then click each additional file or folder you want.