[Nottingham] web space security

[Rennacker Ed]

Hello, all!
I recently bought web space for ; erm ; for fun. It is linux based with 
shell access and now I need to know:
what is this .hta thingy. What do I do to keep guests from wandering my 
images folders (for example) What sort of security(ies) can I use?
I want to read logs and email myself when 'events' happen. I want to set 
up the mail server for imap and keep others from using it to send stuff 
unnecessarily, etc.
TIA
eddacker