hello mohamed elsedawy,

     please follow these steps.

   * Click on the menu button  to open the menu panel.

  *  Click your Firefox Account email or display name (you might need to sign in first.)
      As an alternative, click your account avatar Icon signed in in the toolbar. 
 
*  Click Sync Settings (or click Set Up Sync…, if Sync has been disabled).
            The Sync panel of your Firefox Options page displays.
   If the Sync panel shows Syncing: ON, click Change…. If it shows Syncing: OFF,
         click Set Up Sync… to turn syn  on. 
  
*   In the Choose What To Sync dialog that opens, select the check boxes next
           to the types of information you want to sync just like bookmarks,history ,login and password etc.
 *  Click Save Changes.

Please see this support article:
https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer

Tell us where you are having a problem.