Holding the recently removed black casing in your hand notice that silver circular module connected to the casing.

Using your prying tool gently press down on one of the golden springs coming out of it. Apply enough pressure so the speaker module is ripped off its sticky foundation.

Once this is removed take the new speaker and fit it in at the same place. Be sure to apply a suitable amount of pressure with both finger and thumb to ensure it is stuck to the sticky tape once again.

Follow the steps backwards to put the phone back together.