you can press menu (4 squares, bottom left) then sounds or wallpaper, your original wallpapers and sounds are stored on your phone. if you would like to make your own ringtones you should get an app called ringdroid or tone picker, when you download a ringtone or wallpaper its stored on your sd card, open your file manager and find the app folder or look in mobile, media, or downloads as different apps store things in different places. To get to the stock ringtones and wallpapers you'll need root explorer as they are located on your phones internal storage under system/media.