Ok... you know html, so you know about opening and closing tags...
One warning, in XML, ALL tags must be closed! For that matter, XML parsers are allowed to just give you an error message and quit if the XML is not "well formed."
What XML can do for you: XML allows you to structure your data without worrying about formating, which is mostly what HTML deals with. Most of what "learning XML" entails is learning a package to read and write XML files. The writing is pretty simple, just design your data format and write a program in almost any language to write the data to disk with a few XML tags around it to allow the parser (the reading part) to identify the component parts. You can even use a text editor to create or modify your data, at least until you get fully automated.
Do you know Java, C/C++, VBasic, etc.? The languages you know determine what parse you'll want to use.
Rose/Miros