Save attachments to database and Rails application public directory

I am new to ROR and learning it.I am using Rails 2.3.5. I have a form
where I can attach multiple files. I need to save these attachments in
my db and also in a directory in my application directory. I dont want
to use paperclip plugin as I need to learn File system as well as how to
create dir and save these attachments into it. So any
references/tutorials would be highly appreciated. Please help.
When I submit the form I get the params in the console as

Processing ReminderPluginController#create_reminder (for

at 2013-10-05 19:52:14) [POST]
Parameters: {“reminder”=>{“subject”=>“Hello”, “email”=>"",

My first thing

“controller”=>“reminder_plugin”, “select_batch”=>{“batch”=>“2”},
“recipients”=>“20”, “select_department”=>{“department”=>""},
But I have no idea about creating directory and saving attachments in