Create Note and Assign to a Entity.

Sample code which will create a note and attach to the specified Entity (Specify Entity Name and GUID of the Entity Record)

CrmService service = GetCrmService("http://192.168.150.221:5555", "ORGANIZATION", "USERNAME", "PASSWORD", "DOMAIN");

annotation note = new annotation();

note.subject = "NOTE SUBJECT";

note.filename = @"schema.xsd";

note.mimetype = "text/html";

string encodedData = string.Empty;

using (FileStream fs = new FileStream(@"c:\schema.xsd", FileMode.Open, FileAccess.Read))

{

byte[] byteData = new byte[fs.Length];

fs.Read(byteData, 0, byteData.Length);

encodedData = System.Convert.ToBase64String(byteData);

}

note.documentbody = encodedData;

note.objectid = new Lookup();

note.objectid.type = "SPECIFY ENTITY_NAME";

note.objectid.Value = new Guid("F27A627B-DF1A-DD11-AEA5-0003FF90FBC7");

note.objecttypecode = new EntityNameReference();

note.objecttypecode.Value = "SPECIFY ENTITY_NAME";

Guid annotationId = service.Create(note); 

---- HERE you can Initialize CRM SERVICE Object.....

public static CrmService GetCrmService(string crmServerUrl, string organizationName, string userName, string password, string domain)

{

    // Get the CRM Users appointments

    // Setup the Authentication Token

    CrmAuthenticationToken token = new CrmAuthenticationToken();

    token.OrganizationName = organizationName;

    CrmService service = new CrmService();

    if (crmServerUrl != null &&

    crmServerUrl.Length > 0)

    {

        UriBuilder builder = new UriBuilder(crmServerUrl);

        builder.Path = "//MSCRMServices//2007//CrmService.asmx";

        service.Url = builder.Uri.ToString();

    }

    service.Credentials = new System.Net.NetworkCredential(userName, password, domain);

    service.CrmAuthenticationTokenValue = token;

    return service;

}

Happy Coding....