Use the search function to find information on the topic you're interested in. This will help you formulate your question in a more useful manner and will also help you get a feel for how people interact here.
Pick a single appropriate subforum based on the subject and content of your question and then post your question there. Try to provide enough information to allow people to prepare reasonable and useful responses.
Bad example: What's the best gun?
Good example: I am interested in purchasing a pistol for self-defense. I have some experience with firearms but haven't ever shot a pistol. I'm married and have a small child. My wife has no experience with firearms at all but would also like to be able to use this firearm for self-defense. We want something that is easy to use, and we also need some ideas on how to make sure we can get to the gun in a hurry if we need to but still make sure that our child can't access it.