getting OAuth token from API .Net [on hold]

I'm working on Visual Studio 2013,using c# with .Net. How can I get Oauth token from API which is already exists? I was watching some tutorials about creating the API and using it, but I don't really want it, just get token from API to my WPF application. Do you know some sensible tutorial or could you help me to solve my problem? I'm just getting started with problems like that.


I would be grateful for help, guys.


edit:

i've got username, password and adress to token. I want to use DotNetOpenAuth.OAuth2 or Microsoft.Owin.Security.OAuth. Should I add some more informations?