If they really are CLASS modules, you have to istanziate them, which means create objects from those classes; then you can call all the object members (Public Subs) just like with any other objects, like a TextField (TextField1.Text =...).
Say you have a class module named "MyClass":
Dim obj As MyClass
obj.Initialize
' No need to use CallSubDelayed to call AnyPublicRoutineWroteInsideYourClass from anywhere (but you can).
obj.AnyPublicRoutineWroteInsideYourClass(Parameters ?)
matter of fact i try to understand when i should use the callsubdelayed in general
Just when the routine must be executed after the next code.
Sub AAA
' ...
CallSubDelayed(Component, "SubName")
' other lines to be executed BEFORE "SubName" here
End Sub
With B4A you need to use CallSubDelayed to call service modules' routines.