Ok, so here is a little video i made of the mirror not working then working. I would like to know why it worked. Im confused about reference planes and mirroring i guess.

mirroring question - YouTube

Why is it, when i select the right plane as my mirror face, that the holes end up in the middle of space? i want them on that face. haha. I then followed the instructions for the assignment and it worked but i have no idea why. Im trying to understand why one way works and another does not.

thanks

EDIT: For some reason, only 5 seconds of the video was recorded by solid works..... ill try again. hold on