C# loop through app.config but only use keys like "service"

I'm looping through a txt file currently to get server names and check a specific services status and start it if stopped. This works perfectly with my service names stored in my app.config. What I want to do is also store my file path, file name, timeout, and any other keys I want to put in the app.config down the road. My issue is when I loop through the app.config currently I only have service names which works perfectly. If I add the other keys that I want to add I obviously will get "Service Not Found". How do I only pick keys that ar开发者_如何学编程e "like" "service". I'm naming the keys "service1", 2, 3, etc.

foreach (string key in ConfigurationManager.AppSettings)
{
    string value = ConfigurationManager.AppSettings[key];

    // Create an instance of StreamReader to read from a file.
    // The using statement also closes the StreamReader.
    using (StreamReader sr = new StreamReader(txtFilePath + txtFile))
    {
        String line;
        // Read and display lines from the file until the end
        // of the file is reached.
        while ((line = sr.ReadLine()) != null)
        {
            Console.WriteLine(line);

            // Check for lines with semi-colon. If semi-colon at
            // line start skip it
            if (line.StartsWith(";"))
            {
                continue;
            }
            else
            {
                ServiceController sc = new ServiceController(value, line);

                //Create new timeout module.
                TimeSpan timeout = new TimeSpan();

                //Write current service status to console.
                Console.WriteLine(
                    "The " + value + " service status is currently set to {0}",
                    sc.Status.ToString()
                );

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You should move to a named configuration section with elements that you define VS using the AppSetting collection.

I'd follow the recommendations here on how to make a custom section in your config file, and then you're no longer finding items by key, but by section.