Add information to README

README.md

@@ -1,7 +1,80 @@
-# Under Construction
-
 Crono — Job scheduler for Rails [![Build Status](https://travis-ci.org/plashchynski/crono.svg?branch=master)](https://travis-ci.org/plashchynski/crono)
 ------------------------
 
-Crono is a background job scheduler (just like Unix cron) for Ruby on Rails, on top of the Active Job framework. You can specify a schedule for Active Job jobs and check execution using a web interface.
+Crono is a time-based background job scheduler daemon (just like Cron) for Ruby on Rails. It's pure Ruby. It doesn't use Unix Cron and other platform-dependent things. So you can use it everywhere.
 
+
+## Requirements
+
+Tested with latest MRI Ruby (2.2, 2.1 and 2.0) and Rails 3.2+
+Other versions are untested but might work fine.
+
+
+## Installation
+
+Add the following line to your application's Gemfile:
+
+    gem 'crono'
+
+Run the bundle command to install it.
+After you install Crono, you can run the generator:
+
+    rails generate crono:install
+
+It will create a configuration file ```config/cronotab.rb```
+Now you are ready to move forward to create a job and schedule it.
+
+
+## Usage
+
+### Create Job
+
+Crono can use Active Job jobs in ```app/jobs/```. The only requirements is that the ```perform``` method should take no arguments.
+
+Here's an example of a test job:
+app/jobs/test_job.rb
+
+    class TestJob < ActiveJob::Base
+      def perform
+        # put you scheduled code here
+        # Comments.deleted.clean_up...
+      end
+    end
+
+The Active Job jobs is convenient because you can use one class in both periodic and enqueued ways. But it doesn't necessarily. Any class can be used as Job if it has a method ```perform``` without arguments:
+
+    class TestJob # this is not active job class
+      def perform
+        # put you scheduled code here
+        # Comments.deleted.clean_up...
+      end
+    end
+
+
+### Schedule Jobs
+
+The schedule described in the configuration file ```config/cronotab.rb```, that we created using ```rails generate crono:install``` or manually. The semantic is pretty straightforward:
+
+    Crono.perform(TestJob).every 2.days, at: "15:30"
+
+You can schedule one job a few times if you want the job to be performed a few times a day:
+
+    Crono.perform(TestJob).every 1.days, at: "00:00"
+    Crono.perform(TestJob).every 1.days, at: "12:00"
+
+The ```at``` can be a Hash:
+
+    Crono.perform(TestJob).every 1.days, at: {hour: 12, min: 15}
+
+
+### Run daemon
+
+To run Crono daemon, in your Rails project root directory:
+
+    bundle exec crono
+
+
+### License
+
+Copyright 2015 Dzmitry Plashchynski <plashchynski@gmail.com>
+Licensed under the Apache License, Version 2.0