$_POST["name"]
this is how the information is sent when you post it. post name is basically whatever the name is of the input form. if there was a text box called password then you'd simply do.
$_POST["password"]
this is an example of inserting information that was posted from the form to the page of your choosing.
$insert_query = mysql_query("INSERT INTO users (user,ip,time,id) VALUES ('".$_POST["user"]."','$ip','$time','NULL')") or die('Error @ 1 '.mysql_error());
lastly this would be an example of selecting information from the table after it is inserted.
$user_query = mysql_query("SELECT * FROM users") or die('Error @ 2 '.mysql_error());
while ($list = mysql_fetch_object($user_query)){
echo "$list->user";
}
hope that helps.