When you post your form you need to tell it to post the form to the frame called _top, the frame _top is always the main browser window E.G. everything displayed in the browser.
You need to add a tag to your <form> tag telling it the frame:
<form action="/post.php" method="post" name="Form" target="_top">
So your complete form would look something like this:
<form action="/post.php" method="post" name="Form" target="_top">
<label>Name
<input type="text" name="Name" id="Name" />
</label>
<br />
<label>Email Address
<input type="text" name="Email" id="Email" />
</label>
<p>
<label>
<input type="submit" name="post" id="post" value="Submit" />
</label>
</p>
</form>
You can also use the target= tag to specify a Frame or IFrame name, if you enter the ID of the frame then the form will change the URL of the frame and not the whole page E.G.
<iframe id="Frame1" width="100px" height="100px" name="Frame1" src="Page.html" />
<form action="/post.php" method="post" name="Form" target="Frame1">
</form>
and your form would post to the frame called Frame1 and the main URL would stay the same.
Hope this helps, if you have any more probs then reply to this and I will put an example on my site.
Regards,
Sam Rudge