i did went to your website...

and i downloaded your example package...

it works.. ^_____^ thanks..

but how to make it to autosave..??

So you just want something in a timer that calls LevelSerializer.Checkpoint() every few minutes. That will save the Resume information.

     function Start()
     {
           InvokeRepeating("SaveCheckpoint", 60, 180);
     }

     function SaveCheckpoint()
     {
           LevelSerializer.Checkpoint();
     }

Will save after 1 minute and then every three minutes

yeah... some thing like that..

would the script create a new file that saves the progress and call it when its activated..??

It stores the resume information in PlayerPrefs - there's just one for the whole game at the moment. If you want to do it yourself you could store the string that is returned from LevelSerializer.SerializeLevel() and load it back using LevelSerializer.LoadSavedLevel(yourString);