Rogue-Deity
"Gabriel, my friend, i have a question concerning the placement of a new RP i wish to start. Suppose i want a science fiction story, that also incorporates elements of fantasy, such as use of magic, and mythical beasts, into which forum would i post this new story?"
Excellent question.
You must determine what is first the primary element. Science Fiction or Fantasy?
So if your story is more about the space, the travel, the cyborgs, the possible steam punk, and anything like that, its more than likely scifi. Example in your case would be, if there is a race of being that incorporate magic into their everyday lives, but the main era is set into the future with technology that we obviously do not posses, then its still scifi.
I referenced steam punk to contrast this point. If you have steam punk, but its still based on technology that could work now, like it could be built in my backyard given the brains, then I would possibly call this fantasy.
So place your time line, try to see what technology you are using, see what balance you have to the description I have given, and if all else fails you, send me the starter and I'll tell you where it goes.
Thanks for the question.