You use the red probe on the ground, it should be the black probe, and with the red probe you do the measurements.

Also it is easier to put the black probe in one of the screw holes, or to the chassis, those are also grounds.

But most important, you seems to use the wrong mode, now you have it on AC voltage.
If you want to measure the voltage, you need to set it on DC mode.
If you want to measure the Ohm values, you need to set it on the Ohm measurements mode.
If you want to measure a diode, you need to set it on the Diode measurements mode.

Dc measurements you do with the 12v dc adapter connected to the motherboard because otherwise you will have no dc voltage measurements.

Ohm, or diode measurements you must do without the power supply is connected to the motherboard.


See the picture for your device settings.

http://postimg.org/image/ybprfmzah/