The target attribute of form tag specifies where to open the action URL.

You can do like following :

<iframe name=myframe id=frame1 src=mydetail.asp></iframe>

<form action=../mydetail.asp method=post target=myframe>

<input type=submit name=DoIt value=DoIt>

</form>    

The target attribute is used with frames to specify the frame in which the form response should be rendered. If no frame with such a name exists, the response is rendered in a new window unless overridden by the user.