I'll post in Twitter the shortcut links using bitly, How can i do this ?
Not perfectly clear what you're trying to do, but sounds like you're looking for the bit.ly API - that link has C# libraries for you.
You will also need to make use of the Twitter API.
Have a good read through those resources, understand how to authenticate (api key etc.), then use the c# libraries to make requests to those services.
You can then shorten urls, and post those shortened urls to twitter.