Activity «Run» can be found in section «Basic».

Activity executes the program C# code (version 5.0). The code should be delivered as C#-script. Within the code all the variables from the current context are available.
For example, if the variable A has been stated earlier, it could be used within C# code.
Attention! The String type value should be inserted into activity property. This means that the entire C# code should be delivered as a string (with commas or within variable) (check image below). This makes it possible to dynamically combine C# code if that's neccessary.