copy and paste ??

I am at a loss. Several times I have attempted to copy a d-mail and paste it onto my word processor, with no success at all. I have an iMac and use Mariner Write for word processing. Is this a doable thing or is there some mystical process known only to people who understand how to talk to a computer ? (That sure ain't me) Sometimes there are d-mails I would like to print, but the text only, without the DG surrounding information. I'd sure appreciate someone's advice on the subject.