When you are preparing a message you can do it offline using any text editor e.g. notepad. Save your file with a .HTM extension.

Then double click on its icon - your browser should start with your file open and properly formatted as we will see it after you post it.

Like Wolfgang I've mostly learned bits of HTML from this forum. Another way to see how other people do it (apart from View/Source) is to open the thread, then save it (File/Save As File). The default extension is .htm. You can then view the source offline (and experiment) using notepad. View your results by double clicking on the icon etc.

Cheers,
Alan