Hi...I'm going to plug a 9v battery..into the Arduino as external power... If I have servos plugged into the 5v pin...will they still get 5v and not 9v?
Thanks 
I'm going to plug a 9v battery..into the Arduino as external power.
Why?
They will get 5V for a short time then the 9V battery (I am guessing PP3) will be unable to provide the required current, its voltage will fall dramatically and the circuit will fail to work
How can I fix this then?
Yes/no. They will get 5V or less, but the on-board 5V regulator can't put-out much current (Amps/milliamps). Depending on the servos it might work for awhile before it overheats and shuts-down (or "glitches").
A regular 9V battery can't put-out much current either, and if it works you won't get much battery-life out of it.
You need "bigger" batteries and an external voltage regulator. A "switching" DC-DC converter is more efficient than a "linear" regulator. They are more efficient (for longer battery life) and generally they can put-out more current.
Thanks..and how much power do you think I should supply for 4 servos?
Typically, 1 amp per servo.
Exuse me for asking..but how many volts is one amp?
1 amp per servo at 5 volts.
Four servos, 4 amps at five volts.
So....20v for 4 servos? Or did I get that wrong?
Yes, you got it wrong.
Even when I spelled it out for you.
Please tell me how many volts I need for 4 servos. Do I need 5v?
Do I need 5v
Yes, they each use the same 5V supply, but make sure that your power supply can supply 4 amps as they will use up to 1 amp each
Im not really clear...how should I power 4 servos with an external battery...
Should I plug it into 5v and then power it with a ceartin number of volts battery?
Please give me a guidline to how to power 4 servos.
Get a pack of four AA cells.
Connect the '-' terminal to the Arduino 0V.
Connect the '+' terminal to the red wires on the servos.
Four AAs make 6v...I triend that...and the program didnt work.
Create a 5 V supply by putting 4 AA batteries in series to provide positive and negative terminals
Connect the positive terminal to the positive wire of the servos
Connect the negative terminal to the negative wire of the servos
Connect the negative terminal to the GND connection of the Arduino to provide a common GND
Connect the servo control inputs to your chosen servo pins on the Arduino
Power the Arduino from USB to start with and off you go
Four AAs make 6v...I triend that...and the program didnt work.
The batteries were flat or connected wrongly
Four AAs is what RC hobbyists have been using for decades.
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UM...my question was different ...how would you power this without a USB. How would you power the Ardunio Board and the 4 servos that get 5v.