And how I can install TWRP to use for root my device?
Go to HTC dev site. Register. Log in. Look for "unlock bootloader" option. Click on it. Follow instructions. Great, you have now unlocked your bootloader !
Now, in order to unlock bootloader you had to download HTC fastbooot . Open the folder where that HTC fast boot has been extracted.....
Now, previously downloaded Superuser and Twrp files......
Place them in that folder where you extracted your HTC fastboot files.
Right click on empty space anywhere inside that folder while holding "shift", and you will get an option to "open cmd window here". Click on it. Type "adb devices". Your phone should show as some numbers followed by the word device ( "1234567 device").
Your device should be recognized and you can continue to the next step. If it isn’t recognised then you should re-install all the USB Drivers for your device.
Next, enter the following command line in CMD in order to flash the TWRP Recovery files:?*fastboot flash recovery "name of downloaded recovery".img.
When the TWRP Recovery file is successfully installed, CMD will display a confirmation message. Disconnect the device from computer now.Use the Volume buttons to select ‘HBOOT’ option on your smartphone and select it by pressing Power. Test to see if the RECOVERY mode works by selecting the ‘RECOVERY’ option. Your phone should boot into TWRP Recovery mode now and this means that the install has been successfully completed.
To install Superuser, repeat above steps BUT instead of typing "Twrp xxxxxx.img" type "name of superuser file". Once you have confirmation of the file being sent, disconnect from PC, enter recovery, choose install, and click on the superuser file.
Little tip: I spent hours trying to send both Twrp and superuser files to the phone with all kinds error messages showing inside cmd screen. File too big, can't read file, destination unreachable...... then I found simple solution:
Inside the fastboot folder I created new empty folder.
I copy/pasted Twrp and superuser files inside of it.
Opened cmd folder inside of that new folder and tried sending files again, one at the time. It worked flawlessly straight away.
Little tip 2: if you have trouble writing the names of your Twrp and superuser files in your cmd window, you can do the following:
Type "fastboot flash recovery", press space bar once, now left click on the required file in you fastboot folder (Twrp or superuser) and drag it across into your cmd window.
If you need anything else, feel free to ask. When dealing with this kind of fiddling with your device, no question is stupid or irrelevant.