Thanks for posting this video! it really helped me with creating my own gems.
here is the last one https://rubygems.org/gems/aw-highstock_rails
for pushing it to https://rubygems.org/ i used gem build gem_name.gemspec and then gem push gem_name.gem

very helpful!! here is my first try https://rubygems.org/gems/starrr

is there any help for creating a simple generator in gem ?

Now wait a second why didn't you have to use the gem build and gem install commands before including the gem in the gemfile??