This program helps you with your sentence structure, grammar, it picks up overused words, clichés and vague words in your writing.
The element of style by Strunk White Kalman
There are many writing book out there. The element of style is a grammar rule book which explains all the grammar issues such as dialogue, verbs, commas and many more.
Another good program. It helps you plan your ideas, your characters and scenes for your book. They also have templates to follow if you want to write a short story,
Your imagination is an import tool. Let your imagination run loss. Be inspired to create a story, find your inspiration from things you see or hear. Use your imagination to create a person, place or story.
You have the programs, you have the imagination now get your pen and paper or open the laptop and start writing. Let the story flow.
Attend a short writing class whether online or in person. There are book authors, editors or publishers who can help you with improving your writing. You get feedback from your peers and tutors. Make sure you do your homework on the courses you choose.