public AsyncResult[] create([System.Xml.Serialization.XmlElementAttribute("metadata")] Metadata[] metadata) {
            object[] results = this.Invoke("create", new object[] {
                        metadata});
            return ((AsyncResult[])(results[0]));
        }
        

            var force = new ForcePartner.SforceService();
            var logRes = force.login("xxx", "xxx");
            force.Url = logRes.serverUrl;
            force.SessionHeaderValue = new ForceAPITest.ForcePartner.SessionHeader();
            force.SessionHeaderValue.sessionId = logRes.sessionId;

            var ms = new ForceMeta.MetadataService();

            ms.Url = logRes.serverUrl;
            ms.SessionHeaderValue = new ForceAPITest.ForceMeta.SessionHeader();
            ms.SessionHeaderValue.sessionId = logRes.sessionId;

            ForceMeta.CustomField cf = new ForceMeta.CustomField();
            cf.description = "Favorite fruit";
            cf.fullName = "Account.favFruit__c";
            cf.label = "Fav Fruit";
            cf.type = FieldType.Text;
            cf.length = 25;
            cf.lengthSpecified = true;

            ForceMeta.AsyncResult r = ms.create(new ForceMeta.Metadata[] { cf })[0];
            while (!r.done)
            {
                System.Threading.Thread.Sleep(r.secondsToWait * 1000);
                r = ms.checkStatus(new string[] { r.id })[0];
            }
            if (r.state == ForceMeta.AsyncRequestState.Error)
                Console.WriteLine("Error : {0} {1}", r.statusCode, r.message);
            else
            {
                Console.WriteLine("Done, added new field to Account");
            }