// Global the object.
global $board1_db;

// SQL query. Replace all parameters with question marks (that's how PDO does it).
$sql = 'SELECT member_name
FROM {db_prefix}members
WHERE id_member = ?;';

// Array or parameters. Params must have the same number, and order as question marks in the the SQL.
/**
* $param_array = array(
*   $identifier => $value,
* );
*/
$param = array(
    1 => 1,
);

// Assign a variable to the data returned from the function.
$myid = $board1_db->getone($sql, $param);

// You know this part.
echo'<pre>', print_r($myid), '</pre>';