Just go right ahead and ask about your question, and make sure to name which game it is.
Including tons of extraneous rules about the game and gameplay would only act to obscure your actual question, so leave that stuff out. We encourage questions to focus exclusively on the pertinent details, and the Stack Exchange network has a practice of cutting out things like signatures, salutations, and unnecessary backstory. If you did include all those details, they'd probably just get removed by an editor (such as me).
Anyone who's answering your question should already own the game and be a player who understands it well. Such a person doesn't need the game explained to them.
Anyone else can google the game if they feel they've got a decent chance of answering it anyway despite not having played it. That's a risky move and not something we necessarily encourage since it's difficult to have confidence in an answer like that and they can just easily be totally wrong.