You cannot use embedded pictures in HTML Hep file or HTML pages. You will have to select each equation, copy it to the clipbaoard and save it in a program that can convert them to pictures and insert then into your document as 'link to file' pictures.
See Chapter 15: Using Pictures for more information.
Equations in Word are effectively embedded pictures. Such embedded pictures do not work so you should select them using cut & paste and save them as a BMP in something like PaintShop Pro.
Then insert these BMPs into your document as 'link to file pictures' (Insert | Picture | Link to file).
When creating HTML, EasyHTML/Help replaces these link to file pictures with IMG references to GIF files, so you will need to create a GIF version (use PaintShop Pro) to put with your HTM files.
You could use GIFs in Word but putting a BMP in is better because it them means your GIF file can be made transparent (transparent GIFs do not work in Word 6)