Making An operation system

I want to make my own Operation System. but I want it to be quikly made so. and I also want to use redworks as basic platform mostly for the account system but with a few uppgrades like secure it more than it was

I want an Os that is pretty secure

and I need lot of API to this Os

so when I am done I am going to upload the basic Os I have. so my question is

1: is it wise to use shells to split all the programs? (easier if u want to edit 1 part)

2: can you split account system in 3 pices? 1 for login. 1 for deleting user and 1 for creating users?

You questions aren't clear to me.
1 ) Do you mean running multiple programs at once? How could the shell (which is a program by itself) help with that? You'll have to look into coroutines for that.
2 ) What do you mean by "pieces"? Programs? Functions? Computers? All of that can be done, but why do you need this?

If you don't know much about lua (I can't know, just saying) then I suggest starting with a few simple programs. If you have a look at the OS section of the forum, you can see it's cluttered with people posting a os that is or a boot screen or a copy of Ndf-jay's tutorial. Again, maybe you're an advanced computercraft user, then sorry for this last bit.

me and one person is working on the Os.

you can look it up here http://www.computercraft.info/forums2/index.php?/topic/19605-manual-os-alpha-a-secure-login-os/page__fromsearch__1

Could you clarify your questions?