Feathertwo is very simple setup, it basically goes:

Battery -> link -> Feathertwo battery inputs (the single pair of red and black wires at one end) -> red pair to one motor, black pair to second motor (other end of esc).

Be sure to check the polarity from battery to esc, red to red, black to black before powering it up for the first time, as reverse polarity will damage the feathertwo.

Plug the two rx connectors into your rx, white wire top, into the Ele and Ail inputs. The Feathertwo has a builtin BEC and will provide power to the receiver.

You might want to connect the two motors to the esc via screw terminals before soldering, so you can swap them around if one drive motor is spinning the wrong direction on inputs.

Once you're happy it tests out OK with screw terminals, would recommend soldering XT connectors for everything and labelling them for future reference.