where can I put my photos if my icloud is full?

See the article Manage your iCloud storage - Apple Support

Click on finder > Go > home > your user name > pictures > Photos Library.photoslibrary just right click on it and click on show package contents > click on masters folder to get selected , copy the complete master folder ( use command and C keys ) , again close the finder window , click on Go > Home >( paste use command and V keys ) over the shared folder .

Photos can’t be transferred directly from iCloud to an external hard drive for that you need to set up iCloud photo library see the article Set up and use iCloud Photos - Apple Support

And its preferences Change preferences in Photos on Mac - Apple Support , open finder > Go > home > your user name > pictures either drag and drop Photos Library.photoslibrary to an external hard drive , the second method is right click on Photos Library.photoslibrary and click on show package contents in the upcoming column , you can also drag and drop complete masters folder to an external hard drive that is connected .

Also as per the article Back up the library in Photos on Mac - Apple Support

• Manually copy your library to an external storage device: Drag the Photos library (by default in the Pictures folder on your Mac) to your storage device to create a copy.