I have rooted my s3 and older device but just didnt understand it here. So I use odin to flash twrp.
Then I flash su ap to the phone without odin. Now my last question is the L link u gave me is that what I use to flash su or do I just download it from playstore
---------- Post added at 02:20 AM ---------- Previous post was at 02:07 AM ----------
Now I think I understand I use odin to flash root
then flash phone without odin a su apk
then I followed the L support link u gave me then ill be able to use the national ive hot spot right?
No, I don't think you understand. You use Odin to flash a custom recovery to a Samsung device or a stock image, bootloader, etc. Then you use the custom recovery to flash a ROM that is rooted or flash a SU zip that has the binaries and or some other goodies for root. However, this does require you to read, a lot, since there are several different version and updates for this phone. The link that has been provided is a download for an app that you would install after you have root, but before you tried to do any of this you should have read and read some more until you understood what you were doing. From the post that you have been placing in this thread you have not read any of the links I have and others have provided and don't know what steps you were trying to do, so I not sure if I can help.
The best thing to do is to use odin and flash a stock tar, but you have to read, read, read. You need to know what firmware version you had before doing this, if not you can mess the phone up bad.