How do I Check dc power supply using multimeter

My speaker system's DC adapter looks like not working but I am not sure and before buying new one I need to check it. I have digital multimeter but I am not sure how to use it. Multimeter is with a knob dial and it points to various direction. I am not sure which one to use because last time I tried to use it I rendered it useless, now I have purchased new one.

Help...

First you need to check output from this dc adapter. Now want to check its circuit or only output ? For output, set your meter at V area where it says 12V and test the output.