You should work through the tutorial topics in the order listed, because the later ones build on the content of the earlier ones.
The annotated examples are:
- A simple METAR for Karlovy Vary Airport (no trend forecast)
- A volcanic ash SIGMET for Shanwick Oceanic Flight Information Region
- A TAF for the fictional airport YUDO
- A more complex METAR report for EDDF
- "Bulletinizing" IWXXM reports
- Extended XML content in IWXXM documents