How to migrate data from old MacBook Air to my new one?

millyguide wrote:

I need to be guided to migrate data from my old Mac book air to my new one

Here are the instructions:

Transfer to a new Mac with Migration Assistant - Apple Support

Do you have any specific questions about the migration?

You haven't provided any details about your old MacBook Air (model/year/internal storage size) or your new Mac, so it's kinda hard to guide you in the best direction.