Can't get the value of post, how to solve

Unable to get post value

Beginner PHP, why the above can not be the name and password to secret.php, resulting in output every time you input an effective username and password?
secret.php
Create short names for variables
if ($_post[' name ']== ' &&$_post[' password ']== ')
{
Visitor need to enter a name and password
Echo '

Please input an effective username and password

';
}
ElseIf ($_post[' name ']== ' root ' &&$_post[' password ']== ' 123 ')
{
Echo '

Welcome to the New world!

';
}
Else
{
Echo '

You is not welcome!

';
}
?>

------Solution--------------------
You need to add the Name property to the input control so that the browser submits the value to the server
Username



Password

