Try using the following:
PHP Code:
$result = mysql_query($query) or die(mysql_error());
Note that mysql_error() is only for your benefit. You don't want that to actually be shown to users (and potential script kiddies and others with the intent to breach your security).
The "or die(mysql_error())" part simply says if mysql_query($query) returns FALSE (means there was an error), output whatever mysql_error() returns and then stop processing the page after that. Also, try this for your query:
PHP Code:
$query = 'CREATE TABLE mycms ('.
'id INT NOT NULL AUTO_INCREMENT KEY'.
'username VARCHAR(10) NOT NULL, '.
'password VARCHAR(10) NOT NULL)';