How to write connection string in web config file

<?xml version="1.0"?>

<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->

<configuration>
    <system.web>
        <compilation debug="true" targetFramework="4.0" />
    </system.web>
  <appSettings>
    <add key="ConnectionString" value="server=localhost;user id=sa;Password=surandai;database=IEB"/>
  </appSettings>
</configuration>