PHP/JAVASCRIPT/MYSQL problem

Unity Engine
1

i have tryed an d tryed and tryed. but i realy dont get it. i got my mysql database with logins and passwords… i can login to my website and save my username in sessions. how do i check the sessions in unity and add

SESSION[Username]

to my var Username ="";
in unity?

2

you need to use the WWW class and talk to php.

3

i have read unifycommunity.com and http://answers.unity3d.com/questions/3560/how-can-i-send-and-receive-data-to-and-from-a-url-i-e-server-side-scripts-web and Unity - Scripting API: WWWForm. but do i need to Build it to web or can i check it from the unity editor. and how do i tell the browser to send data like

<form action="" method="post" id="loginform">
  <input name="username" type="text" id="usernameid" />
  <input name="password" type="password" id="passwordid" />
  <input name="login" type="submit" id="submitid"  value="Login"/>
</form>