Creating such shapes and writing text to the images is a work that can be done using Graphics. The .NET framework exposes a
System.Drawing[
^] namespace, which can be used to work with these types of problems in programming.
Although this is not the way of working with Graphics and images in WPF and this System.Drawing namespace is better defined for Windows Forms application, but you can use it to work out the common tasks for creating a simple Ecllipse, Write text to the Graphics object and then save it in a file.
To be more precise and contexual to the WPF and the XAML markup, you can go to
this[
^] MSDN document and learn about Graphics in WPF.