Writing chord symbols might be done with regular letters and signs, like the ones on your keyboard. But it won’t look very good. For a flat you will have to use a b, a triangle for a major seventh doesn’t exist and you won’t be able to write extensions in superscript. Creating beautiful chords is quite a task, both in a text editor and in a music notation program.
I’ve developed a font which makes it easy to create beautiful chords. Create the chords is done by simply typing regular characters from your keyboard, and it’s easy to put the chords above the lyrics. Or you might use the font in your music notation program. Here is an example of how it might look:
Everything in pink is made with this font, using keyboard input. The chord on the top right for example is made simply by typing B7<9/D#. The font itself takes care of the sizing and positioning of the letters and symbols.
More examples of the font are on www.chordsymbols.com. The font is for sale on www.myfonts.com.