could not find schema information for the element

I know this is a common error and checked my properties for a schema which I have.  I have 101 warnings. Below is the file. This is an older program.

<?xml version="1.0" encoding="utf-8"?> <configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0"> <system.web> <authorization> <allow roles="Administrators,Editors" /> <deny users="*" /> </authorization> </system.web>
<location path="Default.aspx"> <system.web> <authorization> <allow roles="Administrators,Editors,Contributors,Moderators,StoreKeepers" /> <deny users="*" /> </authorization> </system.web> </location>
<location path="AddEditProduct.aspx"> <system.web> <authorization> <allow roles= ...