The "linear" regulator you have linked is functionally the same regulator that is already on the Arduino.
With these types of regulators the efficiency is the input voltage minus the output voltage. You're wasting (11V - 5V) / 11V = 54% of the battery power. If you want longer run time you should use a "switching" regulator; check eBay for a "LM2596 module" (~$2) or visit a hobby store for a "battery eliminator circuit" (abbreviated "BEC" or "UBEC"). A switching regulator will waste only ~10% of your battery power.
thank you for the link. I was actually looking at that too. I usually power my device with a 5v wall outlet adapter, but I'm going to be using the device on-the-go and I was just wondering if the 7.4v will fry my board or not. I'm new to this.
then can I just plug in a 7.4v 3cell lipo directly to the board?
First you should figure out how many cells your lipo battery really has.
A 2 cell lipo battery will have a voltage range of around 6-8.4vdc and is nominally rated as a 7.4 volt battery.
A 3 cell lipo battery will have a voltage range of around 9-12.6vdc. and is nominally rated as a 11.1 vdc battery.
Either can be used to power an arduino board via it's external DC power supply connector or Vin pin, but the 2 cell battery will be more efficient because of the use of a linear voltage regulator on the arduino board.
You should consider adding a fuse to the LiPo supply since those batteries can supply huge currents
if there is a short - the fuse prevents the wiring from melting / catching fire. Add an inline fuse to the
+ve supply close to the battery.