Turn off the circuit power
Set the multimeter to current mode
Select AC or DC current as needed
Move the red probe to the correct current input jack
Leave the black probe in the COM jack
Open the circuit where you want to measure current
Connect the multimeter in series with the circuit
Turn the power back on
Read the current value on the display
Start with the highest current range if unsure
Turn off power before removing the meter
Return the red probe to the voltage jack after measuring