Before uploading your first episode you need to create your podcast. Check how here: How do I to set up my first podcast?
Once you've set up your podcast, you are now ready to upload your first podcast episode. To start, log into your RSS account, select "My Podcast" select "New episode."
1. Add your episode title (required)
2. Add your episode description (required)
3. Add Season number and episode number
5. Check if the episode contains explicit contents
6. Add episode keywords (optional but recommended)

7. Add your audio file (required)
Max file size: 600 MB
Recommended format: mp3 or m4a
File name with standard chars, for example: "episode1.mp3", "episode2.mp3" etc ...
When you submit your podcast, keep in mind that the upload process may take a few minutes depending on the audio file size
Do not close your browser until the process is completed
Select "Save changes"
8. Publish your episode or schedule your episode
9. Wait the upload process
10. Great, you uploaded your first episode!