@eskehacettepe
Start with Beginner level learning books. Purchase book used via Amazon or some other source convenient for you.
Example books:
Beginning XML 3rd Edition
XML Beginner's Guide
Many, many books are available.
There are also online courses and tutorials: Google words and phrases starting with "XML online tutorials".
Example link (not a recommendation or endorsement):
Online XML Training
Learning is a very personal thing and you must be motiviated enough to begin on your own using whatever means are directly available to you.
No one here is able to devote the time and effort needed for individual training or to do any such work for you.
Maybe help with a
specific question or two. However that requires that you clearly ask the question(s), explain what you believe is the problem and/or answer, show your work, and cite references.
What efforts have you made where you live (not asking) to obtain the necessary training and skills?
Have you ever taken any sort of coding classes? There is much more to learn than just XML.