Set connection string in web.config and call in asp.net

<connectionStrings>
    <add name="SLMFConnection" connectionString="Server=174.122.52.131;Database=abcdb;Uid=admindb;Password=abchenry123;" providerName="System.Data.SqlClient"/>
    <!--<add name="SLMFConnection" connectionString="Data Source=.;Initial Catalog=ConsultPlus;UID=sa;password=tiger123"/>-->
    <!--<add name="SLMFConnection" connectionString="Data Source=.;Initial Catalog=abccms; Integrated Security=True"/>-->

  </connectionStrings>


using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;



 public SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["SLMFConnection"].ToString());
    public string conStr = ConfigurationManager.ConnectionStrings["SLMFConnection"].ToString();