Hi,
I am trying to integrate SalesForce in to my asp.net C# application. So currently i am able to implement direct login in my application. But i want to implement the OAuth 2.0 login, So for that i am able to get the access and Refresh Token successfully, now the issue is how to do any operation using access token. Like for direct Login we have a method 
bindding.Login(Username,password);
So can any one please suggest me how can i authencate the using using access token. thanks in advance.

I want to insert contact to salesforce, I'm using developer.force account. How can I insert contact? I can't use upsert() method because I"m unable to specify External Id field. Can I create External Id field for connected application using developer account?