How to set up and when to use your emergency fund

Dear Dr Pesa,

I had a lucrative job before the pandemic but I unfortunately got the axe as an effect of COVID-19. I have since gotten a new job with significantly less pay, Sh30,000 per month. I don’t want to experience the same trauma I did for the past three month in the cold. Please advise on how I can set up an emergency fund and more importantly, what can I use it on and what should I not spend it on?