Réponse:

-because I didn't knew

- tu dois supprimer (where as she)

- I looked around not I watched around me

-supprime ( I began to stress and frightered ) remplace la avec (I was so terrified at this moment)

- ( I screamed with fear and her .....) ça n'a auccun sens c'est une traduction française , remplace avec ( I screamed , it was horrible ,she supprised me

- (I began to watch little bit more the thing) tu veux dire ( I began to study her strange body ) ?

I was walking in the forest to kill this strange thing. I was alone versus her, it was terrifying because I didn't know where she was whereas she, she was seeing me.

I was walking yet and yet when all of a sudden ( suddenly est correct mais "all of sudden" est préférable ) I heard cracking wood. I began to stress and be frightened. I watched around me but nothing was here when suddenly something jumped on me.

It was her ! Her* teeth was neon blue.

I screamed with fear and anger (pas besoin de mettre "the" ) but I managed to catch my knife and I killed this strange creature.

She was black, a very dark black, and her blood was as her teeth. She was terrible to see.

But I killed her. The pride in me, I decided to leave but strangely I felt like heavy. I closed my eyes and I [...]

Je me suis permis d'ajouter quelques mots (en italique) pour renforcer un peu ce que tu dis :)

His : adjectif possessif utilisé si le possesseur est masculin.

* Her : adjectif possessif utilisé si le possesseur est féminin.