Hi,
SharePoint doesn't provide API for Windows Store apps. But you could try to use WCF API to connect to the server. Please refer to this thread:
http://social.msdn.microsoft.com/Forums/en-US/winappswithcsharp/thread/f93292a4-3c9c-40d8-a4c5-2ccee815ef5a
Aaron MSDN Community Support | Feedback to us Develop and promote your apps in Windows Store Please remember to mark the replies as answers if they help and unmark them if they provide no help.