Step::1 Login to your WHMCS.
Step::2 Begin by going to Utilities & click on Link Tracking.
Step::3 Click “Add a New Link”.
Step::4 Enter a name to identify the link and then the URL the user should be forwarded to when followed. Then click over Add Link.
Step::5 After adding the url for tracking, click the Edit icon next to it.
Step::6 Now copy the tracking URL and Click on Save.
Check out the video tutorial to get the procedure in detail. You may read the blog as well.