how do you access icloud photos from a MacBook air? it is a simple and logical question, yet you don't answer it. LOL

If you have iCloud Photos turned on, access them in the Photos app on a MacBook Air. You can also access them using an internet browser in the Photos app at www.icloud.com

If you have iCloud Photos turned on, the photos on the device are the same as on iCloud, with the possible exception that some of them may be space-saving optimized versions if you have that option turned on. You view them in the Photos app on an iOS device or Mac. You can also login to icloud.com and go to the Photos app there. See: Set up and use iCloud Photos - Apple Support

If you have an iCloud Photo library already in the cloud you have two options to access the photos:

1 - go to iCloud.com, sign in and access the library there.k

2 - in your local library go to the Photos/iCloud preference pane and enable iCloud Photos. Also make sure the library is the System Photos Library in Photos General preference pane. Depending on the size of the library in the cloud it may take up to a week to download all of the photos to your library. If you don't have enough room on your MBA to house all of the full sized photos then enable "Optimize Mac Storage" so that sized reduced versions will be stored on your MBA.