Well for me atleast,

I want to make an server were people can log in discuss matters of importance, download and upload files and I want to make it safe.
The real problem i have is i don't know where to start, at first i figured i'd do an ftp server and have all the anouncments and such in the root as text files but quickly realised how unpractical that is.

Id love for it to work like this:

1.you conncet to the computer (probably by ip or dyndns)
2.it prompts for your username and password (easily controled by me)
3.sucsessful login brings you to a screen with options for conversation area or files

I'd like the user managment to be powerful enoghf so that if I wante'd i could kick someone out and ban them. Or be able to have ratios and such for up/downloading.

I getting new hardware for my pc sometime next week, so i'll be able to use the old hardware as my server, i have a nat router and other computers on the network, and i'd like to be able to remotely controll the server (so i can hide it waf=0)

What OS do you think i should use i thinkin about some linux but my knowledge with that is somewhat limited, and I have even less experience with unix. But the point with this project is that it's a learning experience, so the fact that i don't know something is not a problem. I want to learn. Is there software that does this or do i have to write some code myself? How hard is it to make safe?

thank you for any and all help