Teller isn't completely silent, but instead he communicates non-verbally. Doing that is just as hard as communicating verbally.
You need to improve your speaking skills. Start by reading out loud to yourself, standing up. Then move to reading standing up in front of a group - maybe your parents / family. Then, see if you can volunteer at a local library for a kids story time and read to them (with expression!). That will get you comfortable being the center of attention.
Next, practice complimenting people. If you are at a store, compliment the clerk on a piece of jewelery -- "that is a really nice ring." Compliment your friends - "I really like those sneakers" or "that is a cool colored shirt." Compliment three people a day for a couple of weeks.
Then, move on to asking people questions. "did you get a haircut?" "are those new sneakers?" "what did you do over the weekend?" "did you travel or stay home for Thanksgiving" "did you see that new Marvel movie?"
Then, start telling stories. "You wouldn't believe what happened to me this weekend...." "I read this article on the internet about..."
Once you do that, patter is a combination of compliementing people, asking questions and telling stories. Also, scripting your presentation does help because you already know what to say. There are some great effects that come with great scripts (not just say-do-see patter where you say what you are doing, do it and then tell the audience to see what you have done). I'd also be glad to help you script your effects.