No OS installed on Huawei Ascend y300

I rooted and unlocked the bootloader on my Huawei ascend y300. It came with and was using Android 4.1.1 until I had to restore.

I got rid of the OS, and now it doesn't boot. I have TWRP installed and also a copy of Gapps Andoroid full stock 4.4.2 signed zip. I have Windows, Mac and Linux on standby. How can I reinstall Android?