If I've understood your comment correctly, the problem is not with editing
the HTML, but with displaying
When you use:
the output is automatically HTML-encoded. This is to protect against cross-site scripting vulnerabilities.
So, if you've entered: "This
is a test
", the output will be: "<b>This</b> is a <i>test</i>"
To have your output treated as HTML, you need to use the Html.Raw