Are u trying to have your <form ..></form> within a already existing <form..></form> block. If yes it will not work.

Crude but easy soln : Next to your Submit Button include this:

&nbsp;&nbsp;<input type="button" value="Cancel"
onclick="parent.location='http://www.gossamer-threads.com'" />

replace gossamer-threads.com with your url

BTW, if you use Reset button
&nbsp;&nbsp;<input type="reset" value="Reset" name="reset" class="submit" />

Say on modify.htm it wouldn't clear the contents. It would just clear any thing that you typed extra. But it will not work on any WYSIWYG editor being used in textareas i suppose.

Give it a try