ML6 Type Coordinate Complexes - Drawing a Molecular Energy Orbital Diagram

In class we recently discussed how to draw out molecular orbital energy diagrams for compounds such as NH3 (ammonia). Building upon this, we touched on how to construct a molecular energy diagram for ML6 type coordinate complexes, namely [Cr[NH3]6)3+. I am confused as to where to begin our diagram formation. All I know right now is that we consider that NH3 coordinates to Cr through it's a1 HOMO. I don't know how to proceed beyond this.


