Spoiler
What language are you trying to do a POST call?
The only one I know for sure is PHP with HTML.
HTML (change action= to proper file location)
Code:
<form method="post" action="index.php">
Username: <input type="text" name="username">
Password: <input type="text" name="password">
<input type="submit">
</form>
PHP
Code:
// Variables below become available after form is submitted
$_POST['username'], $_POST['password']
OTHER EXAMPLE
Code:
<html>
<body>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Username: <input type="text" name="username">
<input type="submit">
</form>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
// collect value of input field
$name = $_POST['username'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>
</body>
</html>