If you'd like to set a default rating for all new images added to the system, you can do that on the settings screen.
Ratings - Ratings
Single image
DPG will import star ratings from all popular image editing software (such as Adobe Lightroom). You can also change the rating of any image on the review screen.
Batch updating
In list view, you can easily batch-edit the rating of any selected images.
Use your keyboard's numerical keys 0-5 to quickly change ratings of selected images in list view, or on the review screen.
View by rating
You can view all of the images in your account organised by rating here.Defaults
Uses
For keyword-based sites, the images with the highest rating will automatically be used as the lead image.
Some sites use ratings to control their layouts, see this guide for more information.