1. Get the embeddable form code in MailChimp (read Mailchimp’s FAQ). You can pick various styles, the SuperSlim form is generally best for sidebars. Copy this code.
2. Add a sidebar widget in your layout on Podbean. Use the “text” widget and paste in the embeddable form code you got in Step 1.
3. You can organize your sidebar widgets as you wish to get the layout you want.