I'm not sure what you mean by `save stuff in dos`... the only things that I can think of is if you want to create a .txt/.bat file and save it, or if you want to save files that are already on your hard drive to a disk or something.
Text = type EDIT <filename.xxx> and press enter, type your text, press alt + f then press S, this will save the text file under the filename you have chosen.
If you want to save a file to a disk, go to the directory where the file is located and type copy filename.xxx a:\
if it is a whole directory then copy *.* a: etc...
If this isn't what your looking for, tell us some more details on what your trying to do