I have a sprint s3 and I just rooted my phone and it was done correct. my question is do I need to download the roms to my computer first then copy to my phone.I have been trying from my phone. it downloads but can't open. help please. thanks
Installing a custom ROM implies a number of steps:
Note: Please BACKUP your data before doing anything! Better safe than sorry.
Make sure you have a proper recovery like CWM or TWRP
Download the ROM file off XDA, make sure you download a file made for only your system.
Wipe date and do a factory reset
(optional: make a backup of your stock ROM)
Flash your ROM
Wipe date and factory reset, reboot and $$profit$$