Simple google search found me this: http://blog.spoongraphics.co.uk/tutorials/create-a-realistic-torn-paper-effect-in-photoshop
If you simply want to grab a piece of picture from a website page, just use the snipping tool that comes with windows, save it as a jpg or png then upload it to where you want it to appear, or add effects with your favourite software.
http://blog.spoongraphics.co.uk/tutorials/create-a-realistic-torn-paper-effect-in-photoshop This link worked for me. Thanks for sharing it though.
Just use the pen tool to make your custom selection and then delete the part selected from the table layer
You could use Adobe Illustrator. You could also get something like that off of google and just manipulate the image using photoshop or Illustrator. You can also try Gimp which is a cheaper version of Photoshop.