> 1)Create a separate group for this ftpusers
That's more to the system itself, don't your customers already have a group of their own? If not, they should, use that group on 2) for example.
> 2)These users should login in to their home directory other
> than that nothing should see
Basically you just need the directive
"DefaultRoot ~" (~ means home directory, like "cd ~" in shell)
in your proftpd.conf. It's possible to implement more magic, as proftpd understands ACLs. Also, I used
"DefaultRoot ~ !staff" (the "!" negates the following object.)
which means, all users are bound to their home directory except those in the group staff.
> 3)If i want to remove the shell access for all these users
> how to configure proftpd.conf file
As in 1) - nothing to do with proftpd itself. I usally don't give a valid shell in /etc/passwd like /bin/noshell or the like. Also, noone should be able to get a shell to your system anyway except physically at the console. For instance you can define who's allowed to ssh to your machine and the like.
> 4)Security how to configure this in proftps.conf
Never done myself, sorry.
> I read the documents but i didn't understand fully.
I think the proftpd.conf is pretty good commented, also I think there was a good document on proftpd somewhere in the debian manuals section.