It is quite easy to use: type in some text. When you want some (e.g.) bold text, click on the bold button and type the text to be bold between the <b> and the </b> tags. Similarly for italic.
If you want to insert a link, click on link and replace the "www.somewhere.com" with the real url. Same for an image.
if you click "Preview" a small window will be opened which shows how your text will appear.
BR inserts a linebreak.
If you click on "Reset", all your text will be cleared.
You can also use html tags which are not offered by the buttons, they will still show up in the preview.

If you are finished (if the preview looks like you want it), you can select (highlight) your text and copy and paste it into the textbox for answering (or creating) a posting.
HTH,
MudGuard