Please tell me I'm confused here
Where to find the novel writing function on qidian's cellphone version app?
There's none on the app. When you want to use your phone just use google chrome and on the upper right corner of the browser there is three horizontally aligned dots, click that and look for the desktop site below and click that. After that the browser will change from mobile to desktop version of displays. Then search webnovel.com and click create button on top of the site it will direct you to inkstone.webnovel.com