[Javascript] Closing pop-up window on form submit

[javascript@xxxxxxxxxx (Jay Wright)]

I have created a small set of web pages, that will open a pop-up window with
javascript, present the user a form, and then, on submit, close the pop-up
window and reload the main site page. 
Below is the form code that I am using. This works, except, of course, that
the data is never POSTED to /content_upload.jsp. The window closes and the
"opener" web page is reloaded with "/main_page.jsp", but the data is never
processed. 
What is the work around. Is there something I can do in the form that will
allow the post to take place before closing the page. Or is there something
I can do in the /content_upload.jsp that would do the processing and then
close the window? 
Looking for a JavaScript guru to lend a little advice. Thanks, 
Jay 
------------------------------------------------- 
PS. Yes, I do need enctype to be multipart, this form is simplified, but
many of them load images. 
<form action="/content_upload.jsp" method="post"
enctype="multipart/form-data"> 
<input type="text" name="data"><br/> 
input type="submit" name="submit" value="Finish"
onClick="self.close();opener.location.href='/main_page.jsp'"><br> 
</form>