Create roles here, in either the Role Ruby DSL (.rb) or JSON (.json) files. To install roles on the server, use knife.
For example, create roles/base_example.rb:
name "base_example"
description "Example base role applied to all nodes."
# List of recipes and roles to apply. Requires Chef 0.8, earlier versions use 'recipes()'.
#run_list()
# Attributes applied if the node doesn't have it set already.
#default_attributes()
# Attributes applied no matter what the node has set already.
#override_attributes()
Then upload it to the Chef Server:
knife role from file roles/base_example.rb