to start backend create a .env file in backend directory with the following contents
PORT=3000
POLYGON_API_KEY="baV4kxJxeUxTjkmh1LZDAAxkWjOzLRd1"
install packages in both frontend and backend directories: yarn
start server with : yarn dev in backend directory
start frontend with : yarn dev in frontend directory
open http://localhost:5173 in browser for frontend
api endpoint http://localhost:port_in_env/api/stocks