First off, you need to register for a Dun & Bradstreet duns number then wait 30-90 days to get reporting. Once you're regularly making monthly purchases on vendor credit and paying your invoices on time, you can apply for the D&B CreditSignal.
This service is free for 14 days and provides alerts for changes in your PAYDEX score, Delinquency Predictor Score, Financial Stress Score, and Supplier Evaluation Risk Rating. After 14 days you'll only be notified of directional changes in your scores.
By signing up for a free account at Nav.com you can get your D&B rating in letter format (A-F) with A or B being good and anything else showing a need for credit repair. If you're a full Nav member ($30-$50 per month) you'll get access to all three major credit bureau reports whenever you want them.