We would really need a lot more information than this, tht. So, you have a newsletter. Is this in html? If so, you can just copy and paste the html into a new page you create in DNN. I'm not sure what the thing is that you don't know based on your question.

But if it sends a newsletter, and it is in html, then I would send a copy to myself, then do a select all on the email, add a new page in DNN (after logging in to DNN as host or admin of course!), and depending on the version of DNN you are using, it will automatically add a text/html module to the page. Edit the text/html module, and paste in the newsletter that you copied. Then click 'update' and that should do it.

I am using asp.net (with FCKEditor) to write my newsletter module. What i want is when i send a newsletter to others, it can automatically write a page in dnn and so if the people cannot read the newsletter in email, they can read it in the dnn site. that is, i supposed i need to write something related to the dnn database... but i don't know how to.

Can you advice me, please?
Thank you.