Hi, Freespirit and welcome to Writewords
Yes, there are magazines, and online ezines which accept Horror - this is a useful website for finding such publications:
http://www.duotrope.com/
Most ezines, however, don't pay for stories they publish, but they are useful for writing experience and confidence building.
Short stories and short writing exercises are a good place to start if you haven't written for a while - you might like to take a look at how-to-write books such as Margret Geraghty's The Five Minute Write.
However, the best way to write a novel is to get stuck in and write the novel.
There is a lot to learn and you should treat it as a marathon, not a sprint - the majority of published authors wrote several novels before finally managing to get published.
Good luck,
NaomiM
<Added>oops, typo: The Five-Minute Write
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