ROM in MD5 file Customization

Hi, I'm a total ignorant in terms of android rom development so, please be patient! :)

I have a MDF file (AP_G531FXXU1AOH1_CL693190_QB5886620_REV00_user_lo w_ship.tar.md5) obtainded using Samsung KIES. I've been using this file with ODIN to restore my stock ROM, everytime some ROOT method is unsuccessful! :)

My question is: can I somehow edit the contents of this file so I can ROOT my phone? If I remove the md5 extension and leave the .tar extension I can unzip the file; these are the contents of the file:
boot.img
NVM.img
recovery.img
system.img

Any ideias?

Phone Model: SM-G531F
Baseband version: G531FXXU1AOG3
Build number: LMY48B.G531FXXU1AOH1