In Google Tag Manager, select an account. The Containers page appears.
Click your site’s container in the list. The Tags page appears.
Click "New Tag" from the Container screen.
Select "Google AdWords" as Product
Choose "AdWords Conversion Tracking" as tag type. Click Continue.
Configure tag by adding the "Conversion ID" and "Conversion Label". Click Continue.
From the pop-up, click the "New" button. Input the Thank You page.
Name the tag "AdWords Conversion Tracking" and click "Create Tag".