I was thinking of controlling 3 servo motors using Ardunio uno , but the problem is that i am not able to power all of them at once just by power delivered by the Arduino uno . I am currently not able to buy any shields but you can suggest me appropriate shields so that it can help me in the future (ofcourse it wont help this time , because as i told you , i wont be able to buy any shields now).So can you please tell me how to externally power these servos so that i am able to deliver enough power as well as control it using Arduino uno . ( I basically need the schematics of the circuit that will make it work) . I would be really thankful if you are able to help me!
A shield is not necessary - although there are servo breakout shields which help with distributing power to lots of servos (screw terminals on the shield). Just wire the servos to their supply, common grounds with the Arduino and connect each servo control pin to an Arduino pin.
The only thing different from what you were doing is the Servo power goes to just the servos.
Trying to power servos from the Arduino 5V is never a good idea, motors and such like should never share power with logic chips.