you run the command
fastboot oem lock
But you should know that the bootloader will NOT show as "LOCKED", it will show as "RELOCKED", so if your hope is to keep your warranty or whatever, you can't. HTC will always be able to tell that you di...
Nimm mal UnlockRoot und versuche es damit einfach Handy mit USB Kabel an PC und auf Root klicken ;)
You should try UnlockRoot, it`s easy and it works for many phones.
I too! PLease do a own section for it!