Default [Q] How do I push zip file from PC to tablet in TWRP?

I did something stupid and I am embarrassed to say I don't know how to get out of it.

I didn't back up my ROM, and I ended up wiping everything. I lost the zip file that I had and now I can't flash it. I am unable to use TWRP's menu to mount the USB. The only option I see mount USB-OTG but it says unable to mount. How do I mount and transfer the zip file? I guess I have to use adb. But I am unable to get it to work. I've tried:

adb push update.zip

after setting the recovery in sideload mode, but nothing happens.

EDIT: never mind. I figured it out. For anyone else, here is what I did:

1) download adb 1.08
2) Put the zip file in the same folder as the adb.exe
3) Run adb usb
4) Do NOT put the tablet in sideload mode. Do nothing there. In fact I rebooted back into recovery.
5) Run adb push <name of zip file> /sdcard/

Nothing will appear to happen for a minute or so. Then you'll get a line to the tune of <kb> in <s> or something. That means it pushed the file to /sdcard/
Samsung S4 - VirginROM