Configuration :: Connecting To DB In Hosting Site - Visual Studio 2008 C# And SQL Server 2008?

I'm creating a website and I'm testing resgistering and Log-in.

I followed a simple tutorial to create a Log-in in Visual Studio C# template which generated a SQL Server database.Locally the Log-in and registration page works perfectly. The problem is that when I upload my site to the hosting site the navigation works but the Log-in and Registration forms send an error when clicked "Register" or "Log-in". I contacted the site and they upload my database the way it should be because I was doing it wrong. I can see all my files including the data base.

They commented me that I had to do a connection string to the data base so the login and registration forms can work. I don't understand how to do that, I know the connection string has to be declared in the Web Config File, the thing is that I don't know how to write that code and link it to my data base in the hosting site, in fact I have sample code but I don't know just what do I need to put in it.