You event class must be self-managed, pls find a way how to implement:

event.save

event.destroy

event.find

because this functions event must know, not db manager

Pls use https://github.com/arbox/ruby-style-guide/blob/master/README-ruRU.md

For example event.rb file written Python-like code styling, not Ruby. Pls use 2 spaces, not tabs!

classes files usually put in /lib subfolder, pls do it

Here is no README file, so user can't find any info about this program. Pls add README.md with following info:

1. About project
2. Required dependencies
3. How to install/bootstrap project
4. How to run and list of parameteres

As I see, it I have not sqlite gem - program will not work

You need to use Bundler to manage dependencies. Pls create Gemfile, add sqlite there

Team work required