how add connection string

</configSections>
    <appSettings>
        <add key="strLocalCon" value="Data Source=EASY-857AC062F0;Initial Catalog=aaa;Integrated Security=True"/>
    <add key="strLocalCon1" value="Data Source=EASY-857AC062F0;Initial Catalog=aa;Integrated Security=True"/>
    </appSettings>
    <connectionStrings>
        <add name="VeePurchases" connectionString="Data Source=EASY-857AC062F0;Initial Catalog=aa;Integrated Security=True"/>
    <add name="VeeSale" connectionString="Data Source=EASY-857AC062F0;Initial Catalog=aa;Integrated Security=True"/>
    </connectionStrings>

//
    SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["VeePurchases"].ToString());