What is use of paint

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

Paint is a low end drawing program built into Windows.

Paint is what I use to quickly copy, paste, and save images. It reads from the clipboard, so copy/paste is easy. Also, you can printscreen, and see it in paint.

Paint is an atrocious application

Consider instead:
Paint.NET - Free Software for Digital Photo Editing (http://www.getpaint.net/)
Inkscape. Draw Freely. (http://www.inkscape.org/)
GIMP - Windows installers (http://gimp-win.sourceforge.net/stable.html)
Picnik - edit photos the easy way, online in your browser (http://www.picnik.com/)

Where you can edit and create images. You can copy a imaes and change according your colour need .