Inserts typicaly send the signal present at the trimpot (First knob at the top of the chanel)out to a device of your choice...compressor, eq effects etc.
NOTE: The whole signal will be routed through the insert jack, and the returning signal must also come back through it , or you will not have anything!
Inserts use a (Stereo) Tip, ring, sleeve 1/4"
jack.
The inserts differ from the effects/aux sends in this way.... You can send a partial signal out these, while still having the original sound present at the faders, EQ and pan etc.
Ask more specific questions, and tell us what you are trying to do....
Sincerely;
Dom Franco