Creating .rtf files

CMA,

   Changing the default file save in Word is easy: go to tools/options/save and select your format.  As for giving you the option to save in different formats, select the 'save as' button and it will allow you to amend the format for word docs there.  Changing wordpad's default save may prove difficult.  however, you can select to 'save as' in Wordpad as in word and select the docs you mention of.

dankh has solved first half of question and should get 100 points.  
  I can now open Word files as .rtf by default.

 Now what I want to be able to do is open or create .rtf files by default with Wordpad, not Word. (When I open an .rtf file, Word opens it. Although if I first start Wordpad, then use Newfile, it will be an .rtf file.)
I think I need to add  some key to the registry under .rtf but I am not sure.

CMA,

  If i understand the latter part of your comment correctly, you can have Wordpad open RTF files by default.  Go to Explorer/view/options/File Types and find 'Rich Text Format.'  From there, you should be able to edit which program to use when you open up a RTF file.  If this works, tell me to post an answer.

CMA,

   One more suggestion:

Once you instruct the computer to use WordPad to handle RTF files, you can create a shortcut to a xxx.rtf file and that will open up WordPad with a .rtf extension.  That is, create a blank .rtf file (name it something like default.rtf) and click on that to use WordPad.  When you save data written to that default RTF, all you need to do is hit save and rename the file and it will be saved in RTF format.  You can reuse the default.rtf indefinitely.

We have made more progress. When I open an .rtf file, it opens with Wordpad by default. However, I always get an error message:
"Cannot find file 'C:\WordpadFiles\default.rtf' (or one of its components). Make sure path and filename are correct...'
    Or if I try to open another .rtf file, it does open, but get same error message but with the file name instead of "default.rtf".
   How to get rid of the error message? Perhaps the registry expects .rtf files to be somewhere else?

CMA,

   You probably altered the default.rtf file (renamed it or something).  Try this, delete the original default.rtf file and create a new one.  On this new one, right click it and bring up the properties box.  Check the 'read only' box.  This will protect the original from changes.  Give it a try and tell me how this works.

Wordpad is fairly "dumb"; it's quite possible that there is no way to tell it to create a RTF file.

CMA,

   I think you will have to instruct it manually to save as a RTF file.  Wordpad defaults to .doc and i think the only way to change that is to alter its code.  

CMA,

   However, with the prescribed method above, you can kinda fool Wordpad into saving all docs into .rtf format.

Didn't work but thanks for good asssistance.dnakh should get 200  points.

I finally found the solution to get rid of the error message.
 In wordpad, can tell wordpad to make .rtf files the default editor.