The three kinds of auxiliary file EASISTAT uses, data, output, and command files, are all ASCII files. This means that they are files containing only normal characters like letters, numbers, punctuation and line feeds, and none of the special characters that some word processors use. They may also be referred to as text files or MS-DOS text files. Most word processors nowadays do have an option to edit ASCII files, however sometimes it can be difficult to tell from the manual how to select this option. If you accidentally save the file in the word processor's native format then it will contain additional characters and EASISTAT will not be able to use it.
Try looking for one of the following options in your word processor manual: ASCII, Import/Export text, Save/Retrieve DOS text, non-document mode.
Once you are able to deal with ASCII files the only difficulty you are likely to run into is if your word processor performs automatic reformatting and starts making everything into paragraphs. To prevent this happening make sure that your left margin is set to 0 and your right margin is bigger than the length of the longest line in your file. If there is an option to turn off justification, word-wrapping or reformatting then use it, and if you have the choice when importing text then say that you want hard carriage returns.
It will often be more convenient to use a program specifically designed for editing text files, such as PFE (Programmer's File Editor) or emacs.
Throughout the rest of the manual you will see references to editing data, output, command and graph files. You must use a word processor or text editor which loads and saves files in ASCII format as described above. I would also recommend that before editing a file you always make a back up copy of it in case something goes wrong.