You will need to first download the Android File Transfer Tool
Next download and extract these three toolkits
RootNexus5.zip
TWRP.RecoveryNexus5.zip
UnlockBootloaderNexus5.zip
Inside each toolkit click the Green Android Icon to execute the task
Turn off your Nexus 5 and boot into recovery then run the root toolkit first, followed by the unlock bootloader, followed by the twrp
Via DroidViews