This will depend on what you're wanting from the editor! If you're writing a letter to the editor of the newspaper, you will write different things than if you're writing to a book editor to publish your story. Please edit this question so that it asks a more specific question so that we can answer it!
Yes, "editor-at-large" should be hyphenated.
how to write a letter to an editor of a newspaper expressing concern over lawlesness in the country
Any text-editor will do.
Use a text-editor.
Write a letter to the editor of daily newspaper regarding the problem caused by stray bulls in the locality
A letter to an editor should explain the reason for writing. It should also contain contact information so that the editor can get in contact with the writer.
The best way to learn to become an editor is to become a writer first. Editors must have a strong gasp of language, spelling and grammar, and there is no better way to practice these skills than to write, write, write.
Write to the book company that published his/her book. They have an editor that worked with him/her and they should be able to forward a letter on to the author.
text-editor, for example.
Use a text-editor.
express opinions.
The four parts to writing a letter to the editor are write the headline and a simple greeting, state the argument you're responding to and your position, provide evidence along with what you think should be done, and finally close your letter. If you have all of these components in your letter than your letter to the editor is complete.