How to know when to buy/sell, how to know when it's going up/down

Good day to all Babypippers!!!

I’ve been in babypips school for roughly 2~3 months now.
The question remains the same!!! How do you know when to click that buy/sell?
How do you know if its going up/down?
I know I should narrow the question, but… I would like to get as many feed backs as possible!!!

Thank you Babypippers in advance!