How do I customize a link?

With these four easy steps, you can customize short links for your site and share branded URLs across the web using Bitly.

  1. Buy a URL — Make it Short. …
  2. Create a Bit.ly Account and Set Your Custom Short Domain. …
  3. Set an A Record for Your Short URL to Point to Bitly. …
  4. Verify Your Tracking Domain.

For More Information Please Refer: https://mashable.com/2010/11/17/custom-short-url/