How to Opens More From 2 Accounts Simultaneously in Mozilla Firefox

I never thought that YM only be able to open multiple accounts simultaneously, then it should mozilla too. So I try and get the instructions. Immediately following this tips:

    * Install the add-ons called CookiePie and follow it to finish.
    * Restart your Firefox
    * Use it with open new tab on mozilla, and right click on the new tab and click the Toggle On / Off
       CookiePie.
    * And then open your account  in firefox.
So it's my quick tips,  Hopefully useful ...