The best place to get started is the Discover page where you can see live public parties and private parties that you have access to.
Kast is more fun with friends. Start a party, invite your friends in, and host a watch party or just hangout & play games with your friends.
You can also go to Parties and People pages, and search for a party that you know. You might be interested in for instance finding parties that mention one of your interests in their name.
We like the Kast Welcome Party ourselves, but then again, we might be slightly biased.