How to use EdiTools library for converting XML data to EDI format in C#

Question

Currently I am looking for any EDIFACT package so that I can convert an XML data packet to EDIFACT. I did't find any package, after soo many finding I have found 'editools' package. Github repo link : Editools. How can I convert xml to edi using editools package. And can anyone help me to understand the EDI file format.

var isa = new EdiSegment("ISA");
            isa[01] = "00";
            isa[02] = "".PadRight(10);
            isa[03] = "00";
            isa[04] = "".PadRight(10);
            isa[05] = "ZZ";
            isa[06] = "SENDER".PadRight(15);
            isa[07] = "ZZ";
            isa[08] = "RECEIVER".PadRight(15);
            isa[09] = EdiValue.Date(6, DateTime.Now);
            isa[10] = EdiValue.Time(4, DateTime.Now);
            isa[11] = "U";
            isa[12] = "00400";
            isa[13] = 1.ToString("d9");
            isa[14] = "0";
            isa[15] = "P";
            isa[16] = ">";
            ediDocument.Segments.Add(isa);
            var gs = new EdiSegment("GS");
            gs[01] = "PO";
            gs[02] = "SENDER";
            gs[03] = "RECEIVER";
            gs[04] = EdiValue.Date(8, DateTime.Now);
            gs[05] = EdiValue.Time(4, DateTime.Now);
            gs[06] = EdiValue.Numeric(0, 1);
            gs[07] = "X";
            gs[08] = "004010";
            ediDocument.Segments.Add(gs);

What is this written here...

I try this below lines of code, but I did't understand the code

var ediDocument = EdiDocument.LoadXml("xmlData.xml");

            var isa = new EdiSegment("ISA");
            isa[01] = "00";
            isa[02] = "".PadRight(10);
            isa[03] = "00";
            isa[04] = "".PadRight(10);
            isa[05] = "ZZ";
            isa[06] = "SENDER".PadRight(15);
            isa[07] = "ZZ";
            isa[08] = "RECEIVER".PadRight(15);
            isa[09] = EdiValue.Date(6, DateTime.Now);
            isa[10] = EdiValue.Time(4, DateTime.Now);
            isa[11] = "U";
            isa[12] = "00400";
            isa[13] = 1.ToString("d9");
            isa[14] = "0";
            isa[15] = "P";
            isa[16] = ">";
            ediDocument.Segments.Add(isa);
            var gs = new EdiSegment("GS");
            gs[01] = "PO";
            gs[02] = "SENDER";
            gs[03] = "RECEIVER";
            gs[04] = EdiValue.Date(8, DateTime.Now);
            gs[05] = EdiValue.Time(4, DateTime.Now);
            gs[06] = EdiValue.Numeric(0, 1);
            gs[07] = "X";
            gs[08] = "004010";
            ediDocument.Segments.Add(gs);

            // more segments...

            ediDocument.Options.SegmentTerminator = '~';
            ediDocument.Options.ElementSeparator = '*';
            ediDocument.Save("save.txt");

Please help me to understand this code or EDI file format.