If you're interested in learning more about the possible meaning of dreams and dream symbols, consider learning more about the field. Although we still know very little – including why we dream – new and interesting discoveries are being made.  Humans have tried for centuries to interpret and understand dreams. However, the first modern attempts only came in the early 1900s with the theories of Sigmund Freud and Carl Jung, many of whose interpretive ideas are still popular today. Currently scientists have a range of theories. Some argue that dreams don't really mean anything but are the result of random electrical signals in the brain; others think that dreaming evolved as a defense tool; and still others link dreams help us to process the emotions and events of the day. Looking into dreams may give you insight into your own psychology. But we still know very little about dreams and their function. Dream symbols may not always be universal – that is, they might not apply for everyone – and you probably shouldn't rely on them to make major life decisions. The internet has all sorts of website that purport to give the meaning of symbols like doors, water, fences, and other things. Many are even in handy, searchable “dictionaries.” If this sounds too good to be true, it is. Take these sites with a grain of salt.  Websites will often plug very specific meanings into symbols. Dream interpretation is actually a lot more messy than this. Given how little we know about the brain and dreams, you are better off relying on your own judgment or on the advice of a psychoanalyst.  Dream interpretation is highly personal and varies widely. There may be some symbols that carry a shared cultural or even universal meaning, but these are exceptions to the rule. Don't trust that a symbol really means what the “dream dictionary” says.
Read up on dreams and the dream science. Be aware of dream interpretation's limits. Take online resources with a grain of salt.