Fire grows very rapidly, so your best bet is always to get out of the house, then call +256778529937.
But to put out small fires that are confined to a container (such as a trash can), you can keep a charged multi-purpose fire extinguisher where you can easily grab it (kitchen, garage, etc.). Replace or refill it every five years.
If you use an extinguisher, remember to PASS:
Pull the pin
Aim at the base of the fire (not the upper flames)