declaration/definition and instantiation of COM objects with visual c++?

i need to instantiate com object which is .dll and on local machine in visual c++,i know that it can be done by using CoCreateInstance("clsid") ,but i am confused about declaration.so can anyone explain all steps involved? for late binding as well as early binding

1. is any import/inclusion required
2. how to declare com object ?
3. any other steps required before createinstance (e.g CoInitialize?)

or provide any specific reference involving step by step code

First you have to call CoInitialize and don't forget to callCoUnitialize if initialization was successful.

So your code will have the following structure:

HRESULT hr = CoInitialize(NULL); 
if (SUCCEEDED(hr))
{
    try
    {
        CoCreateInstance(...)
        // ...
    }
    catch (_com_error &e)
    {
        //...
    }
    CoUninitialize();
}

For more information visit MSDN. I recommend you to start with The COM Library and then you should read something about CoInitialize and CoCreateInstance functions before you use them.

This tutorial could help you too: Introduction to COM - What It Is and How to Use It.