I have a adruino uno and i want to connect 6 pair of ir sensors(receiver & sender) , 8 leds and one servo to it ,so how should I supply power to them so that they run smoothly.
"I am not able to connect all elements . . . "
Well show us a Schematic of your circuit so we can comment on it.
Your heading and your actual question are two different things:
I am not able to connect all elements to adruino uno
so how should I supply power to them
You can't connect them all because an Uno doesn't have enough i/o pins: 2x6 + 8 + 1 is 21, which is too many even if you use pins 0 and 1.
Power is a different issue: the ir senders and receivers and the leds might be ok, you would need to provide details of their connection requirements and individual and simultaneous current; the servo will need its own power anyway.
For more I/O pins use a port expander like the MPC23017 or MCP23S17.
Running 6 IR sensors is easy running 6 IR receivers is not, what is the part number?