7805 have three "legs" pins if the IC is facing you.
(1) the left pin is the positive input pin
(2) the middle pin is the common ground
(3) the right pin is the output (i.e.5v)
procedure :
(a)
the TEU104BK has a red output connector (direct output: i.e. Lipo 8.4v will be directly transfer to this connector and finally to the receiver) for you to connect to the receiver. Cut the wire. connect the red positive wire to (1), the black wire to (2).
the cutted wire with the connector: connect the red wire to (3) and the black wire to (2)
(b)
make a buffer using the capacitor, connect the positive leg of the capacitor to (3) and the negative leg of capacitor to (2). This capacitor is usefull when you use large torque servo .