Marriages in Guernsey can involve either a religious ceremony or a civil one. Follow this link for more information.
You will need to give Notice of Marriage if you are planning a civil or non-Church of England ceremony, by attending the Royal Court in person. There is a wide choice locally for couples wanting a religious ceremony; brief details of the island's 10 parish churches are available in the downloads section of this page.
If you have recently married and need to register your new details with various States' departments, soon you will be able to tell them all through one online form, but for the time being you will need to contact them individually.
You may also need to apply for a new: