[Q] I completely messed up my phone. (noob) topic

Hello,
I tried to update the firmware on my phone and completely messed up my phone while doing it. No there is no os left on the phone.
Trying to install a new rom either trough adb or over the external sd also failed.

The reasons for this mess is that I don´t understand what I am doing,
its actually a trial an error process.

I am now really in the need of help.
Please help me.

Information:

(bootloader) version-bootloader: 3.16.0.0000
(bootloader) version-baseband: 1.15.2133156.UA13G
(bootloader) version-cpld: None
(bootloader) version-microp: None
(bootloader) version-main:

(bootloader) modelid: 0P6B10000
(bootloader) cidnum: HTC__102


M8_Ul PVT SHIP S-Off
CID- 11111111

The only thing that is still working on this phone is TWRP 2.8.1.0

So:
what files do I have to flash?

The files I tried to flash didn´t work…
Mainly it said: E: Unable to open zip file. Error flashing zip

Help would be really appreciated.
I am quite frustrated right now.

My operating system is Mac os X.
Thanks.