STEP 1- FLASHING CWM ON YOUR PHONE
1.At first, you’ll need the “adb” and “fastboot” tools. Get them HERE
2.Extract them into a folder, let’s name it “Redmi2” (You can give your own name to the folder. That doesn’t matter here.)
4.Rename cwm.img or philz.img you downloaded above and as “recovery.img” and place it in the Redmi2 folder.
Now the folder will look like this-
5.Press and hold “shift” button and right click in the blank area of the folder and click on “open command promt window here”. The command prompt will open.
6.Now turn off your Redmi2. Wait until it vibrates. After it’s vibrated press and hold “Volume down and Power” keys together until it boots into “fastboot mode”. Now connect the Redmi2 to your PC/Laptop through USB cable in fastboot mode itself.
7.Get to the command prompt now.
Now type: ” fastboot devices ” (without these- ” ” )
8.Once you enter that command, you will get a non-empty name for the device meaning the device is connected. Proceed to enter the next command
9.Now enter the next command: ” fastboot flash recovery recovery.img ”
10. Now this ends… 😛
Type the last command: ” fastboot reboot ”
11.Now your phone will reboot with ClockWorkMod(CWM) installed. CHEERS…
STEP 2- ROOTING YOUR PHONE
1. Firstly get the SuperSU.zip from HERE
2. Now copy the downloaded zip to your sdcard (not in any folder just in sdcard)
3. Boot into CWM recovery by turning off the phone and pressing “Volume UP and Power” button together after the phone vibrates.
4. Once CWM main menu is displayed, select “Install from zip” and browse to the zip that you downloaded earlier and select it.
5. Install the zip. If you get any warning, ignore and proceed.
6. After the installation is complete, reboot your device. (I think you can do that)
7. VOILA..!!! YOU ROOTED YOUR REDMI2
Source : xda developers