A Samsung Galaxy S, that's got to be running 2.2 Froyo or 2.3 Gingerbread isn't it. I had one of them in 2010, and broke it in 2012. Think you'll need to upgrade it to at least 4.1 Jellybean....somehow, custom ROM possibly, like CyanogenMod. There's CM11 for Galaxy S, which is 4.4 Kitkat I believe, which should give you nice colour emoji.
Native emoji support in Android is 4.1 or greater. You can probably install a third-party keyboard will allow you to send emoji, but it won't show in any messages you might receive via Facebook, or in tweets, etc, because emoji has to be supported by the OS, i.e. Android 4.1 or later.