I see this question over and over again on the forum. "I'm unlocked now how do I install custom recovery?" There are numerous ways to do it. If you're rooted, Flashify is a pretty easy way. HOWEVER, I'm going to instruct you in the fastboot method because it can be used later to recover root after an OTA update on unlocked phones. This is something every unlocked user should know how to do.
WARNING: Read FULLY before performing this. Failure to do so will likely get it wrong.
What you need:
o) The oem usb cable that came with your phone (yes, it matters)
o) A USB 2 port
o) A recovery image for your phone
NOTE: This isn't the "where do I get..." thread. Please find the image for your phone BEFORE coming to this thread to learn how to flash it. Thank you.
o) Extract the platform-tools to a folder on your c:\ drive e.g. c:\install_recovery
o) Copy your recovery img file to the same folder e.g. c:\install_recovery
o) Open a cmd prompt to the directory that contains fastboot and the recovery image e.g. c:\install_recovery
o) Put your phone in AP Fastboot mode, and connect it to a USB 2.0 (NOT 3.0) port using the oem usb cable
o) On the cmd prompt, type:
fastboot flash recovery recovery.img
o) Where recovery.img should be the fiilename for your specific recovery img file that you're trying to flash
o) Once it finishes flashing:
unplug the phone, power it off, boot to the menu, select recovery
o) If you fail to do the above step and just perform a normal boot without going to recovery first, you will be posting "I followed everything...it didn't work" posts and annoying me. If you fail to boot directly into recovery and instead boot normal, your custom recovery image that you just flashed will be overwritten with stock recovery, making it SEEM like "it didn't work" when in fact it did, but you didn't follow directions.
Q: Sweet, I got custom recovery! So, uh, how do I use it to install root? I can do that....right?
A: Yes, yes you can!
It's been pointed out to me that we all make this more complicated than it needs to be. If you're using CWM, you will need to get the supersu zip downloaded to your phone or use the adb sideload method to install it in recovery. However, if you use TWRP, it has supersu built in. Once you boot into TWRP and tell it to reboot, it'll prompt you to tell you that "hey root's not detected, bummer! Want for I to install it for you?" If you tell it yes, it'll install the su binary. Now, it's probably going to be an out of date su binary. The very first thing you should do is ensure the supersu app is installed and/or updated from the playstore, then load the supersu app. It will then prompt you to update the binary. I've never found it necessary to use the recovery option of updating it. So you have 3 options:
1. If using TWRP, reboot into TWRP, and tell it to reboot, thus prompting you to install the SuperSU su binary
2. Flash the supersu zip in CWM or TWRP
3. Sideload the supersu zip using CWM or TWRP in their respective adb sideload options.