Inserts and Updates are more simple than Selects, because you don't have to fetch anything. Just call the prepare method:
http://us3.php.net/manual/en/pdo.prepare.php
Be sure to bind the parameters (values) that you will be inserting or updating:
http://us3.php.net/manual/en/pdostatement.bindparam.php
And then call the execute method:
http://us3.php.net/manual/en/pdostatement.execute.php
And finally you can grab the inserted ID using the lastinsertid method:
http://us3.php.net/manual/en/pdo.lastinsertid.php