GP2Y0A02YK0F distance sensor +servo hitec hs-422

Hello
I am planning to use two sharp IR GP2Y0A21YK distance sensors which are controlling a servo hitec HS-422 all this plugged to one arduino, also supplied by a 9v battery.

When I use just one sensor to read the data is working fine, but then I assume I need to add some resistors or capacitors to this circuit. I have no idea of electronics or how to find out which resistors should I use. I have been reading forums and some people recommends to use a 10UF capacitor, another resistors...so I have tried, but seems not to work.
Could anyone help me and give me some resources in order to find out how to measure electricity and how to learn??
Thanks a lot in advance

lso supplied by a 9v battery.

not recomended, better use AA batteries or a wall wart (far more amperes!)

Thanks for your reply, but apart from that do I need any capacitor or resistor?? how can I measure and know if I need any??
thanks in advance

There's no need for any resistors when interfacing with Sharp IR sensors.

Caps are only needed to decouple the sensor power. If you are providing enough power, the sensors will work without the caps, but your sensor data may be noisy. Decoupling the sensors helps reduce this noise.