How do I install the custom ROM with boot.img inside? I have found a custom ROM in Chinese forums for mY HTC ONE SU (t528w) model.

The ROM is zipped and the folders look like below image



I have no idea to install this ROM. Could anybody please guide me to install this. I dont know how and where to place the boot.img. I have successfully unlocked my bootloader and mobile is rooted too.

Thanks
Please check the place where you downloaded the ROM from, it usually contains installation instructions. In most cases, these ROMs use the update.zip mechanism of the recovery mode, as Matthew mentioned. You might need a custom recovery (see clockworkmod and twrp and their tag-wikis, clockworkmod resp. twrp, for examples).

The process then usually is as follows:


copy the .zip to your SDCard
boot into recovery-mode
select to "apply update from SDCard"
navigate to and select your .zip
let it flash
go back to the main menu and select to "reboot device"