How do you test current testing using a multimeter

Which part of the current do you want to test for, Volts, Amps, or Watts ?
Volts is potential difference;
Amps is the current flow;
watts is the usage.
Volts X Amps = Watts

You can test on low volts DC (0 - 48) safely, but higher needs a technician.

For current, set meter to A or amps, and the current has to run from the power source THROUGH a meters wires to the gadget and back to power return; positive to negative. Run the item and read the meter while it is running.

Or read the compliance plate, or look it up on internet and search for details in the specifications.

Thanks