If you think the built-in editor is not strong enough or you don't like it. You can use external editors.

Here I recommend to you two external editors:

1. Microsoft Word

If before installing the WinCHM you have installed the Word, Word will be automatically detected. Otherwise, you can use Tools > Environment Options... > External editors > Detect to add Microsoft Word to external editor list.

After the completion of adding, you can choose corresponding external editor to edit current page.

2. KompoZer

This is a free HTML editor. You can download it from http://www.kompozer.net/ .

1. Unpack the software to your computer.
2. Click Tools > Environment Options... > External editors > Add, then find out kompozer.exe.