Unlocking an HTC desire 510 phone In this tutorial is the method I am currently following to unlock the bootloader.

Just before Step Four there is a paragraph that says:

"The Command Prompt will spit out a token in the form of a very long string of characters. Select it, copy it, and paste it into the applicable box on your manufacturer’s website–make sure there are no spaces!–and submit the form...."

This is the stage I reached. I cannot however find that "applicable box" after numerous searches! Could someone help me find it? Or suggest a better way altogether to unlock the bootloader?
Have you done the process via DevHTC ? ... 

Htc offers a original unlock method here official unlock at HTC site for developers