Hook the butt of the tape measure to the end of the rim board and measure to where the first wood joist will be installed. Make a mark in the center to represent where the wood joist will be hung.
Measure half the width of the wood joist flange on either side of the center mark and scribe the rim board. Scribe a perpendicular line down the side of the rim board at these marks using a speed square; the marks will represent the inside edge of the location where you will nail the metal joist hanger into place.
Place the top-mount metal joist hanger on the rim board. Align the inside edges of the metal hanger tabs with the perpendicular line that you previously scribed. Hammer a single 10d nail through a pre-drilled slot in each tab to hold the metal hanger in place.
Repeat Steps 1 through 3 on the opposite side of the structure so that you can install the wood joist fully at each end.
Slip the wood joist into the metal hangers. Check to make sure that the top of the wood joist is flush with the rim board on both sides of the structure. Insert load or bearing stiffeners between the metal joist hangers, along with the wood joist, and nail them into place with four staggered 8d nails on each side.
Align the metal joist with the perpendicular lines along the side of the rim board. Hammer hanger nails through all of the metal joist hanger's pre-drilled slots.