Hello Luis,
TestComplete allows calling routines and creating instance of classes declared in your .NET assemblies either by using the CLR Bridge, or by using the AppDomain method.
For example, the following code uses the AppDomain method to access the Test namespace declared in the TestedApp application and creates an instance of the TestClass:
var Obj = Sys.Process("TestedApp").AppDomain("TestedApp.exe").Test.TestClass.zctor();
To learn more about creating instances of the class declared in your tested applications, please see the Calling Functions From .NET Assemblies Help topic.
Please let us know if this information does not help or if you have any additional questions.
Thank you.