If someone has granted you the compute.imageUser role, you can access the images in the project by specifying the image project in your requests.
For example, to get a list of images available to you:
gcloud compute images list --project [IMAGE_PROJECT]
To learn how to use an image to create new resources, such as creating an instance, read Creating and starting an instance.
For example, the following command creates an instance using an image called database-image-a from project database-images:
gcloud compute instances create test-instance --image database-image-a --image-project database-images