This post contains C# code to convert decimal degrees into degrees, minute and seconds.  The screenshot below demonstration the code being using to convert a latitude (in decimal degrees) to a correctly formatted DMS value.

Here is the code associated with the button that does the conversion.

private void Button_Click(object sender, EventArgs e) {
    if (sender == this.buttonConvertToDms) {
        if (string.IsNullOrEmpty(this.textBoxDD.Text)) { return; }
        double d;
        if (!double.TryParse(this.textBoxDD.Text, out d)) { return; }
        CoordinateType type = this.radioButtonLat.Checked ? CoordinateType.latitude : CoordinateType.longitude;
        this.textBoxDMS.Text = Engine.DDtoDMS(d, type);
    }
    else if (sender == this.buttonClose) {
        this.Close();
    }
}

Lastly, here is the formatting code.  Unlike similar sample, this code will pad minutes and seconds with zeros and append a N, S, W or E compass heading.

public enum CoordinateType { longitude, latitude };

public static string DDtoDMS(double coordinate, CoordinateType type) {
    // Set flag if number is negative
    bool neg = coordinate < 0d;

    // Work with a positive number
    coordinate = Math.Abs(coordinate);

    // Get d/m/s components
    double d = Math.Floor(coordinate);
    coordinate -= d;
    coordinate *= 60;
    double m = Math.Floor(coordinate);
    coordinate -= m;
    coordinate *= 60;
    double s = Math.Round(coordinate);

    // Create padding character
    char pad;
    char.TryParse("0", out pad);

    // Create d/m/s strings
    string dd = d.ToString();
    string mm = m.ToString().PadLeft(2, pad);
    string ss = s.ToString().PadLeft(2, pad);

    // Append d/m/s
    string dms = string.Format("{0}°{1}'{2}\"", dd, mm, ss);

    // Append compass heading
    switch (type) {
        case CoordinateType.longitude:
            dms += neg ? "W" : "E";
            break;
        case CoordinateType.latitude:
            dms += neg ? "S" : "N";
            break;
    }

    // Return formated string
    return dms;
}