Saving a Picture
  You can save both newly created pictures or pictures that you
  are revising.
  To save a new picture.
  1.  Choose the Save As...  menu item from the File menu.  A
      dialog box appears.
  2.  Type a file name using the format filename.img.
  3.  Click on OK.
  To save a revised picture that already has a file name, choose
  Save from the File menu.  Paint saves the new version of
  your picture.
  Additional topics:
  *   Using the Tool Palette
  *   Printing a Picture
  *   Viewing Pictures with CDA Viewer
  *   Exiting Paint
  *   Overview of Paint