What is forgiveness really? Does it mean just not being upset by something in past, or telling oneself they shouldn't be mad?

What is mindfulness? I've heard that it means being in the present, but I'm not sure how to do that. When I meditate my mind wanders and I can't help but feel like I am doing it all wrong.

What is a love? How do you know if someone really loves you or not? Is something you can't feel only something you can give?