[Unsolved] How to attach an attachment on a unit

Need help, I have so many attachment models, but can find a way. On the other threads, doesn't make sence to me. Help please.

Attachment Point Names:
overhead (floats over the unit's head, but doesn't sway with)
head (sways with the unit's animation)
chest (also good for wings)
origin (usually at the base of a unit's feet)
hand
foot
weapon (for heroes)
sprite (for buildings)
medium (for buildings)
large (for buildings)

Attachment Point Modifiers:
left
right
mount (for mounted units)
rear (for quadrupeds)
first (for buildings)
second (for buildings)
third (for buildings)
fourth (for buildings)
fifth (for buildings)
sixth (for buildings)
rallypoint (for buildings)

ya im having the same problem i have a marine and custom gun models but i dont know how to but them on the marine please help btw:marine is already weaponless

Make a custom spell out of an item ability, that way it won't display on the unit, and then make the spell do nothing(in other words if you took +dmg spell make it give 0 dmg) and under attachments in the spell add your model to it and then point out where you want it to be "attached to" (see Just Spectating's post)

i forget i have a skin with no gun so no sound how do i make it sound like gunfire again??

Hmm, not sure but did you base your unit on the original marine and then change the model? That way it will be the same as the other exept that it has no gun (unless you attach one)