How do you install TWRP after rooting?
To easily flash TWRP while already rooted, you can install TWRP Manager.  After installation: Open it and select your device, select the version of the recovery that you want to use, hit Install Recovery and let the app download and install it.  The app will automatically prompt you to reboot into the recovery.



If you want to ensure that's it's writing to the correct recovery partition, run this command in a root shell/terminal before you do the above:

ls -a -l /dev/block/platform/*/by-name


It should output a line that looks like this:

lrwxrwxrwx 1 root root 21 Dec 16 16:18 recovery -&gt; /dev/block/mmcblk0p25


Ensure that TWRP Manager asks to write to that latter part (/dev/block/mmcblk0p25 or whatever the output is on your device.)



Another option for rebooting into recovery is to connect your device to a PC and run adb reboot recovery.  ADB is part of the Android SDK Tools, which you can get as part of the Android Studio install or stand-alone here.