Unhappy Need Help unpack repack system.img

Hello I was interested with someone here. can help me I want to take a Samsung Firmware and extract its contents. example system.img and add to some of my own applications. Into the app folder in The system.img i has been extract with some software.
Now I want to repackage the contents of the folder. Back to file system.img then to take all img files example
system.img + boot.img recovery.img cache.img + hidden.img + modem.bin and repackaged to TAR file. I will flash it with Odin