@I_love_smut_Anita I suggest you start by making little conversations, writing doesn't revolve around just the scenery but also the actions and emotions of a character. Coming from a fanfic writer it's much easier to built a character based from yourself as the main because relatable is the best way to connect, and depending on the genre it's also important for you to be sure what you're good at first.
Grammar and Vocabulary are also important aspects of this, you might not be good at English but if you're gonna write a book you gotta start with these basics and build your way up in this world! Nobody's gonna teach you a thing about writing, that's something you learn from making mistakes repeatedly and learning from them.
(From a fanfiction writer this is the best advice I can give.)