If you are using Audacity and you are done with your project, simply saving it is not enough. When you save an Audacity project it saves as an .aup3, which is great if you want to keep editing it but not for other folks to listen to it. Instead you will need to export your project, ideally as an .mp3 for other people to listen to (.wav is preferred for preserving your project).
Once your project is exported you can either email people the file or upload it somewhere for people to listen to, like SoundCloud or a podcast hosting service.
Preserve This Podcast is a great resource for thinking about how you want to save your podcast, and this is especially useful if you are planning a long-running project. They have created a zine that covers the basic principles, and I recommend reading the section on organizing and naming your files.