Use no non-alphabetic characters. Use no spaces. The following screens from Microsoft Word 98 illustrate the process. The following screens from ClarisWorks show the process in that program. Documents created in other word processors can usually be exported to HTML format.
Text files keep all words but loose all graphics and formatting.
RTF files preserve all graphics and most formatting. These files may then be opened and converted to html files using ClarisWorks or Microsoft Word 98. As of this writing, Word 98 gives the best conversion for files with pictures. ClarisWorks is OK for files without pictures. Another alternative would be to open the RTF file with a program such as RTFtoHTML which converts RTF files to web format.