You have two ways to do this as mentioned here
Method 1
$resultSet = $tableGateway->select (function (Select $select) {
// now you have `select` object, do whatever you like
});
Method 2
$select = new Select('table_name');
$select->join(
'another_table_name',
'join condition',
array('column of another table name'),
Select::JOIN_INNER
);
$resultSet = $tableGateway->selectWith($select);