Once you've decided to write a short story, novella (short novel) or novel, you must decide what 'point of view' you want to write in. There are three types of POV.
1st person - This is when you write from the point of view of a character in your story. The advantages are that the reader gets an insight into the characters thoughts, emotions and motives. This is a good POV for people who consider themselves 'character writers'. The downside is that the reader views everything through the lens of that character...although of course that doesn't mean they have to agree with what the character is thinking (e.g. I really don't like Jane Brown. She is so annoying).
2nd person - This is the least used of the three POVs and the one I find the most difficult to explain. I have never written anything in 2nd person but basically it is where the narrator of the story (either the author or one of the characters) is speaking to you as the reader (e.g. I bet you're thinking that right now). It is the POV used for 'Choose Your Own Adventure' books. It's not really my cup of tea but each to their own in this case.
3rd person - This is where the author is the narrator and assumes an overarching 'God-like' position. The author may choose to focus on the thoughts and feelings of one character (e.g. Wayne felt his jugular was about to burst) or change between characters. Usually it is the former but I recently read Territory by Judy Nunn (a brilliant book which I highly recommend) and she changes between characters so you get a fair idea of what is going through each character's mind but she remains the storyteller. In my book, I am writing in 3rd person and it is from the POV of my main character, Brad, so there is no scene without Brad in it. 3rd person is especially good for those who consider themselves 'plot writers'.
Have a play around and see which POV suits you best. Personally, I prefer either 1st or 3rd POV (I intend my next book to be written in 1st person). If you want to read more about POVs then just Google the terms. There are heaps of sites out there which probably explain things better than I do.