It's a bit tricky (even for me) with all the different categories on this forum. Sometimes it's also an overlap (e.g. a problem where you can't get a display working can be a display problem or a programming problem). Each category has a little description. If you hover over a section title like Installation and Troubleshooting, it will tell you what it is for.
I think that in general most people don't care too much but there are people that only look at certain categories when answering questions. Posting it in the (not necessarily) wrong category and you might miss out on their knowledge.
I can't go through all of them; these are some guides
- Installation and Troubleshooting is for problems with the IDE (installation, use) and if your board is not recognised; not for problems with your project
- Introductory Tutorials is for tutorials that e.g. you write, not for questions.
- Programming questions is for compiler errors / warnings or when your code does not do what you expect it to do or if you don't know which how to approach a certain requirement or ...
Since Arduino started expanding outside the Atmel AVR processors, a number of boards have their own category. If it's specifically hardware related, I would place it in the correct category; software related is a bit trickier as that might fit in Programming questions or in the specific category for the board.
And further it's a bit of a feel; I suggest that you do a quick browsing through the different categories (specifically the sub-categories in Using Arduino - Arduino Forum) to see what kind of questions are posted in there; it should give you the idea and you should be covered for most of your questions.