1 . Download TWR.img ( only single file now dont worry ) copy in one folder
2. connect phone to pc boot your phone to download mode
3. open cmd in that folder
4. type adb devices
5. type fastboot flash boot twrp.img
6. fastboot reboot
congratulations now you are successfully booted in to twrp
7. if you just want to boot temporarly just type fastboot boot twrp.img ( this will be helpfull for installing magisk )