You can import Microsoft Word .docx documents to Fade In using File > Import > Microsoft Word (.docx). (Note that Fade In does not support importing older Word .doc-format documents.)

You can also export from Word as RTF or formatted/unformatted text and import from those to Fade In. It may be helpful to try various export/import formats to see what yields the best results for a given document.

More or less reformatting may be required depending on the format of the original document. (Format > Quick Reformat can be helpful for this.)