Q:

How to post XML data via HTTP POST method in windows store apps?

Any samples on consuming rest service post method in windows 8 apps.Please let me know  the possible links on that.

A:

Try this
using System.IO;
using System.Net.Http;
using System.Text;

var objHttpClient = new HttpClient();
var formParameters = "<details><id>1</id><name>test</name></details>");
var objHttpRequestMessage = new HttpRequestMessage(HttpMethod.Post, "http://example.com/page");
objHttpRequestMessage.Content = new StreamContent(new MemoryStream(Encoding.UTF8.GetBytes(formParameters)));
objHttpRequestMessage.Content.Headers.Add("Content-Type", "text/xml");
var result = await objHttpClient.SendAsync(objHttpRequestMessage);

Also check HttpClient sample on MSDN

