New Post: Need help!!!

Hi everyone,
i have just approached to this library in order to complete an university progect,so i am a newbie and please forgive me if my questions can appear stupid for you.

i am just trying some simple function like this

TwitterCredentials.SetCredentials("" , "" , "" ,"");
Tweet.PublishTweet("@ciao");

Obviously between the quotes i set the parameters requested that i have got from the site apps.twitter.com but nothing appear on my twiiter page.
Then i fought i didn't have the privileges to publish so i tried to get a tweet using this function

var tweets = Search.SearchTweets("sampdoria");

but i get this exception System.NullReferenceException.
Can someone help me showing how to set the credential and the correct code for the function i have written?