Silverlight Web Service

Question

Hi,
Am very new to silverlight, and am working on this module where i want to retrieve some data from database, the problem is when i mention column names it dosnt work properly and it gives an error at the return statement....the code is below...


Public Function GetLoginName(ByVal strLogin As String) As List(Of tbl_User)     Implements IService1.GetLoginName
Dim db As New DataClasses1DataContext
Dim matchingLogin = From Login In db.tbl_Users Where Login.UserName.StartsWith(strLogin) _
Select Login.UserName, Login.Password
Return matchingLogin
End Function


Can any1 tell me how to achieve it ..

Thanks in advance