Black Tourmaline aids in absorbing electromagnetic energy. It is used to ground the energy of a space an absorbs toxic/negative energy. BT acts as a protective shield and can be worn on your body to implement an energetic boundary between you and others.
Crystals come into contact and can hold energy and intent from others (hands) so here are ways to clear/cleanse & activate your stone.
To cleanse:. Smudge with smoke and speak intentionally over it. Visualize white light pouring out over your crystals and ask Spirit to dispel all negative energy that doesn't serve you.
To activate/program: Speak the desired intentions over your stone. "I speak/pray the intention of ______ over this crystal for my highest good." Wear the crystal close to your body to connect with it.