First of all you'll need to head to settings - audio within your program and upload your intro and/or outro piece of audio.
2. Once you've tinkered with your transition time and are happy, you'll need to add the intro/outro to a clip. You can preview the effect in program settings - intro as well.
(please note if the clip has previously been published then you'll need to make it private and save the changes before moving to the next step)
3. Head to the clip you would like to add the intro and outro for and select "add program intro and outro"
4. When you're ready to share your clip make the clip public and click "save changes and publish".