Quote:
I am new in coding
If you are a beginner, then you have no idea how complicated the task is: that's why we use third party addons such as iTextSharp.
Here is the PDF file format specification:
PDF reference[
^] - in order to write your own code to generate PDF files, you will need to read and understand tge whole document. As you may have noticed, it's quite large at 1310 pages, and pretty technical. You won't need all of it, probably - but you need to understand it all in order to know what parts you don't need!
This isn't a simple job - I wouldn't attempt it without damn good reasons - but you should finish it in a few years (iTextSharp has been in development since 1998, but the authors probably haven't spent their whole time on it). Good luck!