Assuming you didn’t mark the extension as private or choose to distribute it own your own site, the email telling you that it was approved should have the public URL in it.
The other thing you can do is to log in to the developer hub and do the following:
- Select Tools -> Manage my submissions, or click on My Add-Ons,
- Click on the name of the extension you want to make public,
- On the left, click on the Manage Status & Versions link,
- Change the Listing visibility to Visible,
- If prompted, click Yes, OK, Confirm (or whatever) to allow the change.
Once the listing is public you should be able to do a search for your extension.