Hi Robert,
Suggest you do a search of previous messages to this bulletin board and link in with others researching the name Cretney.
Also join the IOM Family HIstory Society (details at this website under Family HIstory Society,
Do a Cretney search of the IGI at www.familysearch.org
Check out Francis Coakley's site A Manx Notebook also locatable at this website
You sound like a beginner. get a good book on the steps to take in family history research The IOMFHS seel the excellent one on Manx research written by Janet Narasimham.
These are just a few ideas
Kind regards
Elizabeth