This might help:

General HTML FAQ.

As for attaching documents, I'm not really sure.

Thanks for the quick response. Problem is that the information in this word doc is quite length, so to go through an manually add HTML tags would take quite some time, which is why I'm looking for a way to retain formatting or attach the doc directly. Thanks for trying though!

Unless you're planning on submitting Fan Fictions (here's the Submission FAQ), as far as I know, there's no way you can preserve the formatting when copying and pasting from a Word Document to MKO. You'd have to manually add the HTML codes.
As for attaching a Word Document into a post, that I know cannot be done.

Easiest method would be to click on File and to choose either Export as... or Save as...

There should be an option to save as HTML. Then when the file is saved, open Notepad. In notepad go to File then Open choose the html file you created. If you cannot see it look to the little dropdown arrow/box where it says something like *.txt and choose All files *.* Then navigate to your file, open it, copy all of the text between the tags that say < BODY > BODY >, paste.

-Shoe

^this

there may also be an HTML formatting converter for that. alternatively you could copy and paste your document into notepad++ for a plain text version of the formatting you used.