In Web.Config
<connectionstrings>
<add name="MyConnectionString" connectionstring="Data Source=MyPc-PC;Initial Catalog=MyDb;Persist Security Info=True;User ID=sa;Password=12345" providername="System.Data.SqlClient" />
</connectionstrings>
And you can access using
string constr = WebConfigurationManager.ConnectionStrings["webshopConnectionString"].ConnectionString;