ANSWER - I don't think it makes much difference as to what the subject matter at question is. The issue here is the expected etiquette of using a forum, not necessarily using a forum in regard to witchcraft.
So you've gone on a forum, asked a question and got flamed for your ignorance. I'm not going to deny this ever happens but in my experience it happens very rarely for no good reason. Have you perhaps asked a question that has been asked over and over again on the forum and you haven't bothered to do a bit of reading first? Have you ignored forum instructions that the admin has taken the time to post in a "sticky" at the top? Have you made any effort at all to get to know people on the forum before leaping in to use them as a free alternative to buying some beginner books on the craft? Have you in fact jumped in feet first with a long post about your life history before you've even posted a single getting to know you post...?
The behaviours expected in using internet forums are the same as in joining any community. People are willing to help and support one another but it isn't a one way street. You have to make the effort to get to know people and earn their trust. Witchcraft forums in particular (and especially in October, lol) are very accustomed to flash in the pan flavour of the moment people who join, post voraciously for a few days and then disappear into the night. If you want people to take the time to offer you constructive suggestions then give them a reason to think you are worth the time you want them to spend on you. Give before you take so to speak.
I'd also look at the type of forum you are joining. Forums on the internet are often intended for a specific type of person. If you've joined a forum for experienced witches they may well get a bit annoyed at newbie level questions. If you've joined a very established community to ask a question that has been asked every month since they started they may be a bit disgruntled that you haven't flicked through the archives before asking the same question yet again. It might be worth joining a couple of forums as a reader rather than a poster until you can be sure you are a good fit for the community and that it is a community intended for your own level of interest and experience.
Contrary to what a lot of people think internet forums are not always the best place to ask questions. There are teaching sites around but most forums are a place for social interaction and sharing ideas rather than doling out advice and information. There are exceptions and the more you explore the more likely you are to find forums that do welcome new people with questions. But I'll be honest, any forum that is happy to spoon feed you information probably doesn't have that much value. A good forum will encourage you to think and research for yourself and come with thoughts and suggestions rather than just allowing you to join with the sole intention of asking questions.
There are a wealth of places where you can ask questions - some great Facebook pages for example (just stick the word "witch" into FB search). Starting conversations and threads on forum topics will also inspire debate and discussion. But don't go wading in with a mile long post expecting other people to sort your life out. It isn't a reasonable expectation and I can tell you now that witch or no witch, nobody is going to do that for you.