When you created your new hook, there was a form for a template name.

The template you created on the create new hook page can be edited in the admincp >> style manger. Select the Master style while in debug mode to apply the code to all styles. Scroll down to the template name and double click it. Paste the code in the template editor and save. Sometimes you will need to clear the system cache in Admincp >> Maintenance for the changes to take effect immediately.