Are these related?
I will assume not...
1) In VS, open the Server Explorer (Menu: "View...Server Explorer"
2) Right click the database your are interested in, and select "Properties"
3) The connection string is listed in the properties window.
4) Open your Web.Config and below the "appSettings" section add:
<add name="MyDatabase" connectionString="...connection string as per the properties window"/>
Objects and methods:
This is a bigger subject. I assume you have created your class library, and want to use items from them.
1) If you haven't done so, add a reference to the class library in you app.
2) Add a
if you want it.
3) Declare an object of the appropriate class type from your library, as if it was a .NET inbuilt type. for example if your class library defines a class "MyClass" then:
MyClass myInstanceOfMyClass = new MyClass();