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 127.0.0.1 at 2013-10-05 19:52:14) [POST]       Parameters: {"reminder"=>{"subject"=>"Hello", "email"=>"", "body"=>"<p>My first thing</p>"}, "attachments"=>[#<File:/tmp/RackMultipart20131005-8107-o8osmj-0>, #<File:/tmp/RackMultipart20131005-8107-1n1k7pz-0>], "controller"=>"reminder_plugin", "select_batch"=>{"batch"=>"2"}, "recipients"=>"20", "select_department"=>{"department"=>""}, "commit"=>"Send", "authenticity_token"=>"pKT8//ESD5SWvSuelVpOiHw3k30RxrqDOODckUToURs=", "action"=>"create_reminder"} But I have no idea about creating directory and saving attachments in it..