You can see the HTML you inserted by clicking on “HTML Source”. This is all of the HTML on your page, both what you create and what Netscape Composer creates for you.
You can edit this HTML if you choose, but be careful. It is very easy to damage your web page when you edit the HTML directly. I like to “Save” my web page before editing the HTML source directly. This allows me to “revert” to the last saved version if I make too much of a mistake.
When you add HTML by hand, all of your HTML must be in the “body” section: after the <body> and before the </body> that Netscape has already put there for you.