Take time to think about your overall story plan. Consider the story's main character(s) and others and what they will do, as well as the purpose of the story and what you intend to convey. Don't worry about the title if you don't have one -- sometimes those arise during the actual writing process, so rather than spend time worrying about what to call the story, focus on the story ideas first.
Draft an outline by using the set-up and opener ideas, introducing characters, building the central story and then how you will close it. Weave the characters into the draft. Use Roman numerals for headers, and either lowercase letters or another method for sub-headers. An example of a rough outline would be:
MY STORY
I. Bob the Bear is in the burning forest
a) describe Bob
b) describe the forest on fire
c) describe Julie, Bob's young friend
c) forest location and closeness to Julie's house
II. Mother Bear is lost
a) describe Bob's fear
b) build danger
III. Julie's house catches fire
a) Bob the Bear needs to rescue Julie
b) Bob is torn between finding his mother bear and helping Julie
Check the sequences of your story plan using the "who, what, when, where and why" concepts. Make sure you've covered these concepts for each character, such as Who: Bob; what: our hero; where: lives in forest on Planet Biglite, puts out fires for friends, saves Julie; when - here is how you designate what happens at the beginning, middle and end. Each "why" will be different for various characters, intended actions or will vary depending upon the situation -- such as why do I need a fire on a distant planet to teach about the love between friends?
Review and revise the draft outline by filling in areas you may have omitted, adding characters at an appropriate place and building on plot points. For example, you decide the entire story is going to take place on a planet outside our galaxy. You'll need to go back and tell the reader about the planet, then set Bob, his lost mother, and Julie's house into the story's new broader perspective.
Finalize the outline after you have reviewed the drafts of your ideas several times. Each time, you are moving closer to the actual story you wish to tell. When you feel you have included all key pieces to set your story into motion, check for spelling errors, save a copy of the file and leave it alone for a couple of days.
Return to your outline and review it once again. Observe your outline with the "fresh eyes" you've gained from stepping away from it. Check to see if the story still makes sense and the characters all fall into place smoothly. If not, rewrite it accordingly.