Build a Connection and update Contact First and Last Name fields

//update name (build a connection, and update by contact id)
const string application = "YOUR APPLICATION NAME";
const string apiKey = "YOUR API KEY";

var customer = new Customer(application, apiKey);
var client = customer.Connect();

//contactid 105
client.ContactService.Update(105, setter =>
{
    setter.Set(c => c.FirstName, "Joe");
    setter.Set(c => c.LastName, "Bobertson");
});