Oil is pumped from the oil tank on the side to the one on the motor and then injected into the engine from there.
Always fill the big one on the side.
Check the one on the engine to make sure it is full and top off if needed but should always be full if there is oil in the big tank.
Manuals can be had from various sources, these systems are well supported by SELOC but the best is factory documentation from Mercury Marine Brunswick Corp, you may be asked for the engine serial number of your sportjet, keep this number handy as change orders are serial number dependent..