Find a topic that your question relates to. I mean you don't wanna ask how to fix an OS problem in the wallpaper part of the forum, you'd ask in the OS part.
Welcome! Depending on the nature of your question I would suggest the Help section. Additionally, check out the FAQ section you may find answers there.
Use the search function to see that your question hasn't already been answered. If you can't find out what your looking for post a thread in the section that you think is relevant. If you get it abut wrong you will be forgiven as your a new member. One of the helpful mods will move it to the right secion...