If you need to pass it by reference you can't and will need to create a variable, then pass a pointer. If you just want to pass it by value, myFunction(MyClass()) is what you want.
There is a new keyword but it returns a pointer and you have to store that pointer somewhere and use delete on it.
Please, please do us all a favor and find a C++ tutorial and read it though. This is covered in literally every C++ tutorial/book I have ever seen. I try to be helpful but I don't really have the bandwidth to answer basic questions in detail right now. Maybe someone else does, but getting us to re-explain language basics is time-consuming. But either way, unless you start asking things that can't be answered via Google in a few minutes, I'm done.