How do i copy a picture from website

Depending on why I’m copying the picture, I either click and drag it to the desktop (or a folder) or I right click on the picture (control click) and select one of the options in the popup menu like Save Image to Desktop.

You can copy the image using a screen shot:

https://support.apple.com/en-us/HT201361

Or you can press down on the trackpad with one finger and drag a copy off with another finger.

Ciao.