When you are first starting with Podpage and you haven't attached a domain to it, your website address will https://www.podpage.com/(name of show). You can see the name of the show under Settings > Podcast Info
A much easier way to get your address is to click on Podpage logo in the top left corner (the big "P") and then in the upper right hand corner click "Open Website." You will see "Open Website" on many different pages in Podpage. This makes it easy to check any changes you've made.
Once you've got your site setup looking and doing what you want, adding a custom domain or subdomain can boost your SEO, make you sound more professional, and make it easier to remember and share for your audience.
There are many places you can buy a domain (typically around $20/year) such as Namecheap, Hover, Godaddy, and many others.
Then you can add it to your website see Using a Custom Domain.