Modifying an Existing Rails Gem

I'm playing around with MongoMapper and have cloned the repository. I'd like to start modifying the code but am new to Rails and am not sure how to do this.

You can checkout the github repository - http://github.com/jnunemaker/mongomapper

You can extract the source like this:

git clone http://github.com/jnunemaker/mongomapper.git

Which will create a directory with the gem's source in it.

You can then reinstall your modified version using

rake install