php - Notice: Undefined Index in form submission to another page -

i new php , trying submit form using post. form element looks like

<form action="<?php htmlspecialchars($_server["/php/somefunctions.php"]);?>" method="post"> 

both files have session_start(); declared @ top , form doesn't have required field. when open form in browser shows,

notice: undefined index: /php/somefunctions.php in 'filepath' on line 31.

line 31 above mentioned line. if ignore , fill in form , click on submit, gives me

access forbidden!

you don't have permission access requested object. either read-protected or not readable server.

you should use server document root.

$_server["document_root"]./path file

also forgot add echo. without echo php won't display

echo htmlspecialchars();