I'm new as well, but I've seen this issue pop up before.
You can try this:
Step 1) Hide the exising close button by adding a Content Editor Web Part to the DispForm.aspx
Page
Step 2) Add the below style and JavaScript function to the source editor
of the Content Editor Web part
<style>
/*- hide the Exisiting close button -*/
.ms-ButtonHeightWidth
{
display:none;
}
</style>
<script type="text/javascript">
function redirectnews()
{
window.location = "http://www.google.com"
}
</script>
<table>
<tr>
<td align="right">
<input type="button" value="Close" width="150"
onclick="redirectnews()">
</td>
</tr>
</table>
If the above didn't work for you, try checking out this link, what you want to do is setup a URL redirect.
http://social.technet.microsoft.com/forums/en-US/sharepointcustomizationprevious/thread/5f20cc93-9bdd-4cec-9168-16a0a3f095f8