Ok.
I’ll bite, and be the rude one:
It looks to me like you need to learn some basic linux. Learning to traverse and use commandline is a minimum: Linux Tutorial for Beginners - Learn Linux and the Bash Command Line
You also need to look into sftp to learn how to transfer things to a linix box. Filezilla is a good client for that: https://filezilla-project.org/
Then you need to re-read the tutorials given on this forum allready. @tNt and @JayMontana36 has written several point-by-point descriptions for how to install mods, including where they are located, let me search the forum for you on that: Search results for 'install mod' - MineOS Forum
Sorry if I come across a bit crass, but this is really basic stuff that we have to write several times a week. All the info is in the forum all ready, and if the how-tos are to advanced, it may be due to a need of base knowledge.