How to chant for goddess of mercy? What to say? HOW?

I'm 18 years old this year, and I have a god (goddess of mercy) at home from a monk that gave my dad in the temple when my dad wants to buy it but instead the she gave us free. Anyway, so how to chant fir goddess of mercy? And which are the best timing? I am new to this, please help me!! THANKS :)