Write a Salesforce Trigger Template

I'm looking to have a trigger made that creates a new record for a custom object when an existing object (also custom) is updated to meet specific criteria. Existing Object A is updated to meet a condition A new record is created for Object B mapped to Object A. The trigger will map a few field values from object A to object B I have a few scenarios where I need a trigger similar to this one made so what I'm looking for is good documentation in the code in English so I can reuse it. I'll give you access to my dev account to write the trigger on the existing objects.