C# draw a randomly Stoping Point(object) on a circle?

iam writing a program for a randomized game selection. I want to have a moving object around a LiveChart. Which is stoping randomly after some spins. Now my question is how can i make a moving object around the Piechart. Iam asking here because the videos i watched or the dokumentation's i read, dosent explain how it works. And i dont want to copy past something without the Knowledge how it works. Thats why i have no clue how to programm the xaml and the xaml.cs I hope you can help me with this small amount of informations, from my site.

Thanks for all informations.