The next two steps show how to measure low (<600 mA) current.

The iFixit multimeter's low current port has a 600mA limit. If you suspect the measurement will be above that, use the high current measuring method first.

Plug the black lead into the COM port. Plug the red lead into the mA port (the right port on the iFixit multimeter).

Turn the function dial to the milliamp mA mode. If you're measuring Alternating Current (AC), press the blue select button to switch to AC mode.

You can also measure in the microamp μA mode if you know you're measuring minute amounts of current. This changes the measurement range and gives you more precision at the μA range. Even if you exceed that range, it won't damage your multimeter—as long as you don't exceed the port limit (600mA).