Hi,
If you already know how to create and consume
WCF Web Service then you shouldn't have problems.
You could first start by creating a WCF Service Application.
and define all your queries logic which you'll need afterwards to retrieve your datas
in you WP 7 app....
Then once you're done, you can then create a Windows Phone 7 project
in which you'll consume the same WCF service and add the proper
bindings in your list and detail page.
You can have a look at the following link which explains the basics.
Creating a Windows Phone 7 Application consuming data using a WCF Service
http://www.c-sharpcorner.com/UploadFile/UrmimalaPal/1858/Default.aspx
Hope this helps.