@Joe_Ching The only way to place orders is with the Alpaca APIs. Polygon is only for getting market data.
Placing an order is as simple as a single line of code in Python
api.submit_order('AAPL', side='buy' qty=1, type='market', time_in_force='gtc')
Maybe look at this forum post as a good tutorial on using Google colab for an interactive notebook to code and place orders.