I don't understand. I have uploaded my photos to icloud, but photos still use a significant space on my computer storage. Any help is appreciated!

They will. Photos iCloud is a synchronization service, not offline storage. Anything on your device is also in the cloud. And, any changes you make (edit, delete, etc.) on one device will be reflected on all devices.

You can elect to optimize photo storage, which will keep full-resolution photos in iCloud and lower-resolution images on your device. On a Mac go to Photos > Settings > iCloud in the Photos menu

You need to delete the photos that you uploaded to iCloud from your laptop.