Hi and welcome! 
What do you mean by “uploading images”, and what are you trying to do? If you just want to annotate images, there’s no need to upload anything – you can directly pass in a directory of images as the source argument on the command line, and they’ll be streamed in for annotation. As you annotate them, the annotations will be stored in the database.
If you already have image annotations and want to import them to a Prodigy dataset, you can also do that. Just make sure that the examples are formatted in Prodigy’s JSON format. You can find examples of this in the “Annotation task formats” section of your PRODIGY_README.html. You can then either use the db-in command on the command line, or connect to the database in Python:
from prodigy.components.db import connect
db = connect()
db.add_dataset("new_dataset") # create a new dataset
db.add_examples(some_new_examples, ["new_dataset"]) # add examples to the dataset
You can also find more details on the available database methods in the “DB” section in the Readme.