How can I create HTML File

Have you looked at the HTMLReportGenerator. You can use the Text File writer to write the output to a file.

https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_Transformers/Transformers/htmlreportgenerator.htm

I have Multi work space how can I join in one Html file?

or how can i mention that is work space work success or error and also mention that the error