New here - asking for app/site to start writing

Hey there, I'm new here so I'm not sure if this has been discussed before.

Just wanted to ask what apps/sites (free or minimal fees) that you recommend I can start writing about my own experiences, life, anything I can think about, etc.? 

I'm not a writer nor trained but I've done a few. My purpose is not to publish but just to write and improve my skills, plus it's good for the mindset and positive outlook as they say. I find it therapeutic to write so I want to focus on this. :)

Appreciate your recommendations. Thanks!