In the film Chris plays a character called Peter Quill. The following description of this character is taken from iMDB.
Peter Quill is an interstellar adventurer who was abducted from Earth at a young age. After recovering an ancient artifact, Quill must rally an unlikely team of cosmic misfits to prevent a powerful villain from destroying the galaxy.
As well as Guardians of the Galaxy Chris has played a number of other characters in films and TV shows including -
Andy Dwyer in Parks and Recreation
Donovan Timms in Timms Valley
Brett in Delivery Man
Cully in 10 Years
With his performance in GOTG I am hopeful that Chris will get some more big movie roles in the future. He is starring in Jurassic Park and has been rumored to be taking part in The Magnificent Seven.