Miui v8 Galaxy S5 G900T

Does anyone have experience flashing Miui v7 or v8?
I found this link on their website but it doesn't have any instructions. Currently I flashed the zip but i got stucked and had to restore previous rom.
Note: I'm not a developer, I do have experience flashing.
Link:
http://en.miui.com/download-264.html



Regards,
Kendrick O'Reilly

Galaxy S5 G900T Available OS

Hello Guys,

I want to change the OS of my S5, to a different one(not android) or a ported OS.
NOTE: i mean operating system not Custom Rom

G900T T-Mobile unlocked - Want to switch to AT&T stock rom

All the apps are default T-Mobile stuff for which I have no use for. Can I just install an AT&T rom? Cyanogen dose not have a rom Labeled for AT&T, what should I do? I am on android 4 right now and would like to go to 5 or 6. I also had the IMEI changed out, will upgrading android effect it?