In 1st Gear

Hydraulic pressure is applied to the 1st clutch, then the 1st clutch engages the secondary shaft 1st gear with the secondary shaft by the one-way clutch.
The mainshaft 3rd gear drives the secondary shaft via the countershaft idler gear and secondary shaft idler gear.
The secondary shaft 1st gear drives the countershaft 1st gear and the countershaft.
Power is transmitted to the final drive gear, which in turn drives the final driven gear and the transfer drive gear.
The transfer output shaft drives the transfer hypoid drive gear/shaft and the transfer output shaft (hypoid gear).

NOTE: The graphic shows the 4WD transmission; the 2WD transmission does not have the transfer mechanism.

Fig 1: Identifying A/T Power Flow Diagram (1st Gear)

Courtesy of AMERICAN HONDA MOTOR CO., INC.