a spell to summon an orb

I agree with Tombstone. You need more knowledge.

An orb is generally the form of a spirit takes. A sphere of energy is generally the natural shape any energy takes when it is concentrated. Circles are the shape of moving energy.

I'm not sure why you want an energy weapon. If you are this new in magick, you should not be worried about attacking and making enemies you cannot handle, but instead perfecting defending yourself. Think shields, guardians, wards, amulets, protections.