Ptac Install In Chicago How Do I Install Angle Iron Lintels For A New Opening In Exsisting Brick Veneer?

How do I install angle iron lintels for a new opening in exsisting brick veneer? - ptac install in chicago

I am installing two units of PTAC in an attic. They are on the gable walls. How do I install new lintels of openings. The openings are about 42 cm wide and 16 "high. What have the bricks is in good condition. Any help is welcome.