WP-Premium theme, adding subscribe2 “submit by email button”

I have the WP-Premium theme which has the “subscribe by email” button at the top of the page. In the Header.php it says:

<div class="subscribeform">
		  <p>Subscribe via Email </p>
			<form action="enter your feed address here" method="get">
			  <input type="text" value="" class="input" />
			  <input type="button" class="sbutton" value="Subscribe" />
			</form>
 		 </div>

I want to set this up so people can subscribe to my website with just an email address. The plugin i am using, Subscribe2, has a widget which allows users to subcribe via just and email address. I want to transfer the data from this widget to the button that is already available on the theme I am using. My question is how do I populate the above code with the proper informaiton to have the button submit users emails to register with my site. I dont care if I have to use Subscribe2 or not, or even if I have to use another plugin. I do not want to use feedburner or something, i want these to become users of my website, which will allow me to send them nightly post summaries.

Thanks in advance.

PS. I have been looking for the answer to this for 3 straight hours with no luck.