How to write store procedure in sql server

Hi All,

i'm new in store procedure. Now i want to create a store procedure to my project. Below are the criteria that i want:

Table name: visitor_registration. column (Visitor_id, datetime_in, status)

1. search datetime_in at table visitor_registration. 2. if datetime_in more than 24hours, then update the status become "overdue".

I hope someone can help provide me the sample. Thanks