but when I send Html Email to others, it didn't show the way we want,it seems to didn't support fieldset and some css elements in some Email client. Now I am here for help that is there some ways or some modules to change the tags to common html email tags like and add some css to it? I'll appreciate anyone who help me solve this problem.
I think you want HTML format template option to send an email with HTML format.
Now check step 3 at admin/config/system/htmlmail and select "Full HTML".
Now you can config you webform mail setting and select custom mail template and add your HTML tags and inline CSS in div.