Am an international student in china, so most of my fellow international dont have a platform to sell second hand stuff,what they do is create groups in wechat,the main messaging app in china,problem is for them to reach many people to buy their stuff they have to join so many groups. Recently wechat introduced mini programs,apps that run in wechat and uses js,so i made an app where they can post stuff and i bind each post with the users wechat qrcode and id, this way i connect sellers and buyers.
Node.js on the backend,qiniu cloud to store the images and js and wechat's own wxml and wxss on the front end

I really hate it when people say "the codes are not working" ....no its simply code!!!!!!

Am a sophomore too,so take my advice with a mountain of salt.
Learn data structures and algorithms.
Learn git.
Learn to reason about your code.
Learn to debug your code.
Learn the style guide of whatever language or framework you are using.
Learn how to work with others.
Lastly learn to relax,remember its one step at a time.

@pajaja haha i hope so too :)