<p>I'm not good at programming and my trying to open one of my spreadsheet documents.
Below in the basic login im using, I then request a list all my spreadsheet, which is returned in $feed.</p>

<p>And now I'm worried I'm not on the right track with opening a document so I can read and write cells.</p>

<pre><code>&lt;?php

require_once '../library/Zend/Loader.php';
Zend_Loader::loadClass('Zend_Gdata_Spreadsheets');
Zend_Loader::loadClass('Zend_Gdata_ClientLogin');
$user="username";
$pass="user password";

// login
$service = Zend_Gdata_Spreadsheets::AUTH_SERVICE_NAME;
$client = Zend_Gdata_ClientLogin::getHttpClient($user, $pass, $service);

$spreadsheetService = new Zend_Gdata_Spreadsheets($client);
$feed = $spreadsheetService-&gt;getSpreadsheetFeed();

print_r ($feed);
?&gt;
</code></pre>

You're on the right track.  Are you using the information found
http://framework.zend.com/manual/en/zend.gdata.spreadsheets.html
?
Your code is getting a spreadsheet feed which lists all the available spreadsheets, which is an important step.  You'll want to follow the link above to get a list-based feed or a cell-based feed.
The documentation is pretty good I would recommend just reading through it all(yes it's long).