Don't post question for entire project solution .
Search in google to find a solution for that.
Here, i gave you a link to help for your project.
1) Linkedin have a REST based API - http://developer.linkedin.com/docs/DOC-1258
You can create a HttpWebRequest, pointed at a REST endoint, and parse the response however you wish.
HttpWebRequest request = WebRequest.Create("http://api.linkedin.com/v1/people/~/connections/") as HttpWebRequest;
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
StreamReader reader = new StreamReader(response.GetResponseStream());
Console.WriteLine(reader.ReadToEnd());
}