"COM" is short for 'common'.
As Oso said, black in the COM, red in the V ma jack.
You might want to read the manual.
Side note.....the colors illustrate one of the issues with color codes.
With AC, black is hot, white is neutral. Hence, you would typically connect your black lead to the white wire and the red lead to the black wire.
Let me know if you're not confused enough.....